diff --git a/client/src/__locales/en.json b/client/src/__locales/en.json
index 64c6b4b5..92540ea6 100644
--- a/client/src/__locales/en.json
+++ b/client/src/__locales/en.json
@@ -79,7 +79,7 @@
     "no_settings": "No settings",
     "general_settings": "General settings",
     "upstream_dns": "Upstream DNS servers",
-    "upstream_dns_hint": "If you keep this field empty, AdGuard Home will use <a href='https:\/\/1.1.1.1\/' target='_blank'>Cloudflare DNS<\/a> as an upstream. Use tls:\/\/ prefix for DNS over TLS servers.",
+    "upstream_dns_hint": "If you keep this field empty, AdGuard Home will use <a href='https:\/\/1.1.1.1\/' target='_blank'>Cloudflare DNS<\/a> as an upstream.",
     "test_upstream_btn": "Test upstreams",
     "apply_btn": "Apply",
     "disabled_filtering_toast": "Disabled filtering",
@@ -246,5 +246,8 @@
     "form_error_equal": "Shouldn't be equal",
     "form_error_password": "Password mismatched",
     "reset_settings": "Reset settings",
-    "update_announcement": "AdGuard Home {{version}} is now available! <0>Click here<\/0> for more info."
-}
\ No newline at end of file
+    "update_announcement": "AdGuard Home {{version}} is now available! <0>Click here</0> for more info.",
+    "upstream_parallel": "Use parallel queries to speed up resolving by simultaneously querying all upstream servers",
+    "bootstrap_dns": "Bootstrap DNS servers",
+    "bootstrap_dns_desc": "Bootstrap DNS servers are used to resolve IP addresses of the DOH/DOT resolvers you specify as upstreams."
+}
diff --git a/client/src/actions/index.js b/client/src/actions/index.js
index 1bb99064..ad63ed16 100644
--- a/client/src/actions/index.js
+++ b/client/src/actions/index.js
@@ -3,7 +3,7 @@ import round from 'lodash/round';
 import { t } from 'i18next';
 import { showLoading, hideLoading } from 'react-redux-loading-bar';
 
-import { normalizeHistory, normalizeFilteringStatus, normalizeLogs } from '../helpers/helpers';
+import { normalizeHistory, normalizeFilteringStatus, normalizeLogs, normalizeTextarea } from '../helpers/helpers';
 import { SETTINGS_NAMES } from '../helpers/constants';
 import Api from '../api/Api';
 
@@ -452,10 +452,18 @@ export const setUpstreamRequest = createAction('SET_UPSTREAM_REQUEST');
 export const setUpstreamFailure = createAction('SET_UPSTREAM_FAILURE');
 export const setUpstreamSuccess = createAction('SET_UPSTREAM_SUCCESS');
 
-export const setUpstream = url => async (dispatch) => {
+export const setUpstream = config => async (dispatch) => {
     dispatch(setUpstreamRequest());
     try {
-        await apiClient.setUpstream(url);
+        const values = { ...config };
+        values.bootstrap_dns = (
+            values.bootstrap_dns && normalizeTextarea(values.bootstrap_dns)
+        ) || [];
+        values.upstream_dns = (
+            values.upstream_dns && normalizeTextarea(values.upstream_dns)
+        ) || [];
+
+        await apiClient.setUpstream(values);
         dispatch(addSuccessToast('updated_upstream_dns_toast'));
         dispatch(setUpstreamSuccess());
     } catch (error) {
@@ -468,11 +476,18 @@ export const testUpstreamRequest = createAction('TEST_UPSTREAM_REQUEST');
 export const testUpstreamFailure = createAction('TEST_UPSTREAM_FAILURE');
 export const testUpstreamSuccess = createAction('TEST_UPSTREAM_SUCCESS');
 
-export const testUpstream = servers => async (dispatch) => {
+export const testUpstream = config => async (dispatch) => {
     dispatch(testUpstreamRequest());
     try {
-        const upstreamResponse = await apiClient.testUpstream(servers);
+        const values = { ...config };
+        values.bootstrap_dns = (
+            values.bootstrap_dns && normalizeTextarea(values.bootstrap_dns)
+        ) || [];
+        values.upstream_dns = (
+            values.upstream_dns && normalizeTextarea(values.upstream_dns)
+        ) || [];
 
+        const upstreamResponse = await apiClient.testUpstream(values);
         const testMessages = Object.keys(upstreamResponse).map((key) => {
             const message = upstreamResponse[key];
             if (message !== 'OK') {
diff --git a/client/src/api/Api.js b/client/src/api/Api.js
index d20a334a..17df1221 100644
--- a/client/src/api/Api.js
+++ b/client/src/api/Api.js
@@ -34,7 +34,7 @@ export default class Api {
     GLOBAL_QUERY_LOG = { path: 'querylog', method: 'GET' };
     GLOBAL_QUERY_LOG_ENABLE = { path: 'querylog_enable', method: 'POST' };
     GLOBAL_QUERY_LOG_DISABLE = { path: 'querylog_disable', method: 'POST' };
-    GLOBAL_SET_UPSTREAM_DNS = { path: 'set_upstream_dns', method: 'POST' };
+    GLOBAL_SET_UPSTREAM_DNS = { path: 'set_upstreams_config', method: 'POST' };
     GLOBAL_TEST_UPSTREAM_DNS = { path: 'test_upstream_dns', method: 'POST' };
     GLOBAL_VERSION = { path: 'version.json', method: 'GET' };
     GLOBAL_ENABLE_PROTECTION = { path: 'enable_protection', method: 'POST' };
@@ -110,7 +110,7 @@ export default class Api {
         const { path, method } = this.GLOBAL_SET_UPSTREAM_DNS;
         const config = {
             data: url,
-            header: { 'Content-Type': 'text/plain' },
+            headers: { 'Content-Type': 'application/json' },
         };
         return this.makeRequest(path, method, config);
     }
@@ -119,7 +119,7 @@ export default class Api {
         const { path, method } = this.GLOBAL_TEST_UPSTREAM_DNS;
         const config = {
             data: servers,
-            header: { 'Content-Type': 'text/plain' },
+            headers: { 'Content-Type': 'application/json' },
         };
         return this.makeRequest(path, method, config);
     }
diff --git a/client/src/components/Settings/Upstream.js b/client/src/components/Settings/Upstream.js
deleted file mode 100644
index fe24c4d7..00000000
--- a/client/src/components/Settings/Upstream.js
+++ /dev/null
@@ -1,97 +0,0 @@
-import React, { Component } from 'react';
-import PropTypes from 'prop-types';
-import classnames from 'classnames';
-import { Trans, withNamespaces } from 'react-i18next';
-import Card from '../ui/Card';
-
-class Upstream extends Component {
-    handleChange = (e) => {
-        const { value } = e.currentTarget;
-        this.props.handleUpstreamChange(value);
-    };
-
-    handleSubmit = (e) => {
-        e.preventDefault();
-        this.props.handleUpstreamSubmit();
-    };
-
-    handleTest = () => {
-        this.props.handleUpstreamTest();
-    }
-
-    render() {
-        const testButtonClass = classnames({
-            'btn btn-primary btn-standard mr-2': true,
-            'btn btn-primary btn-standard mr-2 btn-loading': this.props.processingTestUpstream,
-        });
-        const { t } = this.props;
-
-        return (
-            <Card
-                title={ t('upstream_dns') }
-                subtitle={ t('upstream_dns_hint') }
-                bodyType="card-body box-body--settings"
-            >
-                <div className="row">
-                    <div className="col">
-                        <form>
-                            <textarea
-                                className="form-control form-control--textarea"
-                                value={this.props.upstreamDns}
-                                onChange={this.handleChange}
-                            />
-                            <div className="card-actions">
-                                <button
-                                    className={testButtonClass}
-                                    type="button"
-                                    onClick={this.handleTest}
-                                >
-                                    <Trans>test_upstream_btn</Trans>
-                                </button>
-                                <button
-                                    className="btn btn-success btn-standard"
-                                    type="submit"
-                                    onClick={this.handleSubmit}
-                                >
-                                    <Trans>apply_btn</Trans>
-                                </button>
-                            </div>
-                        </form>
-                        <hr/>
-                        <div className="list leading-loose">
-                            <Trans>examples_title</Trans>:
-                            <ol className="leading-loose">
-                                <li>
-                                    <code>1.1.1.1</code> - { t('example_upstream_regular') }
-                                </li>
-                                <li>
-                                    <code>tls://1dot1dot1dot1.cloudflare-dns.com</code> - <span dangerouslySetInnerHTML={{ __html: t('example_upstream_dot') }} />
-                                </li>
-                                <li>
-                                    <code>https://cloudflare-dns.com/dns-query</code> - <span dangerouslySetInnerHTML={{ __html: t('example_upstream_doh') }} />
-                                </li>
-                                <li>
-                                    <code>tcp://1.1.1.1</code> - { t('example_upstream_tcp') }
-                                </li>
-                                <li>
-                                    <code>sdns://...</code> - <span dangerouslySetInnerHTML={{ __html: t('example_upstream_sdns') }} />
-                                </li>
-                            </ol>
-                        </div>
-                    </div>
-                </div>
-            </Card>
-        );
-    }
-}
-
-Upstream.propTypes = {
-    upstreamDns: PropTypes.string,
-    processingTestUpstream: PropTypes.bool,
-    handleUpstreamChange: PropTypes.func,
-    handleUpstreamSubmit: PropTypes.func,
-    handleUpstreamTest: PropTypes.func,
-    t: PropTypes.func,
-};
-
-export default withNamespaces()(Upstream);
diff --git a/client/src/components/Settings/Upstream/Examples.js b/client/src/components/Settings/Upstream/Examples.js
new file mode 100644
index 00000000..4ba54852
--- /dev/null
+++ b/client/src/components/Settings/Upstream/Examples.js
@@ -0,0 +1,32 @@
+import React from 'react';
+import PropTypes from 'prop-types';
+import { Trans, withNamespaces } from 'react-i18next';
+
+const Examples = props => (
+    <div className="list leading-loose">
+        <Trans>examples_title</Trans>:
+        <ol className="leading-loose">
+            <li>
+                <code>1.1.1.1</code> - { props.t('example_upstream_regular') }
+            </li>
+            <li>
+                <code>tls://1dot1dot1dot1.cloudflare-dns.com</code> - <span dangerouslySetInnerHTML={{ __html: props.t('example_upstream_dot') }} />
+            </li>
+            <li>
+                <code>https://cloudflare-dns.com/dns-query</code> - <span dangerouslySetInnerHTML={{ __html: props.t('example_upstream_doh') }} />
+            </li>
+            <li>
+                <code>tcp://1.1.1.1</code> - { props.t('example_upstream_tcp') }
+            </li>
+            <li>
+                <code>sdns://...</code> - <span dangerouslySetInnerHTML={{ __html: props.t('example_upstream_sdns') }} />
+            </li>
+        </ol>
+    </div>
+);
+
+Examples.propTypes = {
+    t: PropTypes.func.isRequired,
+};
+
+export default withNamespaces()(Examples);
diff --git a/client/src/components/Settings/Upstream/Form.js b/client/src/components/Settings/Upstream/Form.js
new file mode 100644
index 00000000..245e7d27
--- /dev/null
+++ b/client/src/components/Settings/Upstream/Form.js
@@ -0,0 +1,139 @@
+import React from 'react';
+import { connect } from 'react-redux';
+import PropTypes from 'prop-types';
+import { Field, reduxForm, formValueSelector } from 'redux-form';
+import { Trans, withNamespaces } from 'react-i18next';
+import flow from 'lodash/flow';
+import classnames from 'classnames';
+
+import { renderSelectField } from '../../../helpers/form';
+
+let Form = (props) => {
+    const {
+        t,
+        handleSubmit,
+        testUpstream,
+        upstreamDns,
+        bootstrapDns,
+        allServers,
+        submitting,
+        invalid,
+        processingSetUpstream,
+        processingTestUpstream,
+    } = props;
+
+    const testButtonClass = classnames({
+        'btn btn-primary btn-standard mr-2': true,
+        'btn btn-primary btn-standard mr-2 btn-loading': processingTestUpstream,
+    });
+
+    return (
+        <form onSubmit={handleSubmit}>
+            <div className="row">
+                <div className="col-12">
+                    <div className="form__group form__group--settings">
+                        <label className="form__label" htmlFor="upstream_dns">
+                            <Trans>upstream_dns</Trans>
+                        </label>
+                        <Field
+                            id="upstream_dns"
+                            name="upstream_dns"
+                            component="textarea"
+                            type="text"
+                            className="form-control form-control--textarea"
+                            placeholder={t('upstream_dns')}
+                        />
+                    </div>
+                </div>
+                <div className="col-12">
+                    <div className="form__group form__group--settings">
+                        <Field
+                            name="all_servers"
+                            type="checkbox"
+                            component={renderSelectField}
+                            placeholder={t('upstream_parallel')}
+                        />
+                    </div>
+                </div>
+                <div className="col-12">
+                    <div className="form__group">
+                        <label className="form__label" htmlFor="bootstrap_dns">
+                            <Trans>bootstrap_dns</Trans>
+                        </label>
+                        <div className="form__desc form__desc--top">
+                            <Trans>bootstrap_dns_desc</Trans>
+                        </div>
+                        <Field
+                            id="bootstrap_dns"
+                            name="bootstrap_dns"
+                            component="textarea"
+                            type="text"
+                            className="form-control"
+                            placeholder={t('bootstrap_dns')}
+                        />
+                    </div>
+                </div>
+            </div>
+            <div className="card-actions">
+                <div className="btn-list">
+                    <button
+                        type="button"
+                        className={testButtonClass}
+                        onClick={() => testUpstream({
+                            upstream_dns: upstreamDns,
+                            bootstrap_dns: bootstrapDns,
+                            all_servers: allServers,
+                        })}
+                        disabled={!upstreamDns || processingTestUpstream}
+                    >
+                        <Trans>test_upstream_btn</Trans>
+                    </button>
+                    <button
+                        type="submit"
+                        className="btn btn-success btn-standard"
+                        disabled={
+                            submitting
+                            || invalid
+                            || processingSetUpstream
+                            || processingTestUpstream
+                        }
+                    >
+                        <Trans>apply_btn</Trans>
+                    </button>
+                </div>
+            </div>
+        </form>
+    );
+};
+
+Form.propTypes = {
+    handleSubmit: PropTypes.func,
+    testUpstream: PropTypes.func,
+    submitting: PropTypes.bool,
+    invalid: PropTypes.bool,
+    initialValues: PropTypes.object,
+    upstreamDns: PropTypes.string,
+    bootstrapDns: PropTypes.string,
+    allServers: PropTypes.bool,
+    processingTestUpstream: PropTypes.bool,
+    processingSetUpstream: PropTypes.bool,
+    t: PropTypes.func,
+};
+
+const selector = formValueSelector('upstreamForm');
+
+Form = connect((state) => {
+    const upstreamDns = selector(state, 'upstream_dns');
+    const bootstrapDns = selector(state, 'bootstrap_dns');
+    const allServers = selector(state, 'all_servers');
+    return {
+        upstreamDns,
+        bootstrapDns,
+        allServers,
+    };
+})(Form);
+
+export default flow([
+    withNamespaces(),
+    reduxForm({ form: 'upstreamForm' }),
+])(Form);
diff --git a/client/src/components/Settings/Upstream/index.js b/client/src/components/Settings/Upstream/index.js
new file mode 100644
index 00000000..f622268c
--- /dev/null
+++ b/client/src/components/Settings/Upstream/index.js
@@ -0,0 +1,67 @@
+import React, { Component } from 'react';
+import PropTypes from 'prop-types';
+import { withNamespaces } from 'react-i18next';
+
+import Form from './Form';
+import Examples from './Examples';
+import Card from '../../ui/Card';
+
+class Upstream extends Component {
+    handleSubmit = (values) => {
+        this.props.setUpstream(values);
+    };
+
+    handleTest = (values) => {
+        this.props.testUpstream(values);
+    }
+
+    render() {
+        const {
+            t,
+            upstreamDns: upstream_dns,
+            bootstrapDns: bootstrap_dns,
+            allServers: all_servers,
+            processingSetUpstream,
+            processingTestUpstream,
+        } = this.props;
+
+        return (
+            <Card
+                title={ t('upstream_dns') }
+                subtitle={ t('upstream_dns_hint') }
+                bodyType="card-body box-body--settings"
+            >
+                <div className="row">
+                    <div className="col">
+                        <Form
+                            initialValues={{
+                                upstream_dns,
+                                bootstrap_dns,
+                                all_servers,
+                            }}
+                            testUpstream={this.handleTest}
+                            onSubmit={this.handleSubmit}
+                            processingTestUpstream={processingTestUpstream}
+                            processingSetUpstream={processingSetUpstream}
+                        />
+                        <hr/>
+                        <Examples />
+                    </div>
+                </div>
+            </Card>
+        );
+    }
+}
+
+Upstream.propTypes = {
+    upstreamDns: PropTypes.string,
+    bootstrapDns: PropTypes.string,
+    allServers: PropTypes.bool,
+    setUpstream: PropTypes.func.isRequired,
+    testUpstream: PropTypes.func.isRequired,
+    processingSetUpstream: PropTypes.bool.isRequired,
+    processingTestUpstream: PropTypes.bool.isRequired,
+    t: PropTypes.func.isRequired,
+};
+
+export default withNamespaces()(Upstream);
diff --git a/client/src/components/Settings/index.js b/client/src/components/Settings/index.js
index efa49bdd..e6c39cf7 100644
--- a/client/src/components/Settings/index.js
+++ b/client/src/components/Settings/index.js
@@ -41,22 +41,6 @@ class Settings extends Component {
         this.props.getTlsStatus();
     }
 
-    handleUpstreamChange = (value) => {
-        this.props.handleUpstreamChange({ upstreamDns: value });
-    };
-
-    handleUpstreamSubmit = () => {
-        this.props.setUpstream(this.props.dashboard.upstreamDns);
-    };
-
-    handleUpstreamTest = () => {
-        if (this.props.dashboard.upstreamDns.length > 0) {
-            this.props.testUpstream(this.props.dashboard.upstreamDns);
-        } else {
-            this.props.addErrorToast({ error: this.props.t('no_servers_specified') });
-        }
-    };
-
     renderSettings = (settings) => {
         if (Object.keys(settings).length > 0) {
             return Object.keys(settings).map((key) => {
@@ -75,8 +59,7 @@ class Settings extends Component {
     }
 
     render() {
-        const { settings, t } = this.props;
-        const { upstreamDns } = this.props.dashboard;
+        const { settings, dashboard, t } = this.props;
         return (
             <Fragment>
                 <PageTitle title={ t('settings') } />
@@ -91,11 +74,13 @@ class Settings extends Component {
                                     </div>
                                 </Card>
                                 <Upstream
-                                    upstreamDns={upstreamDns}
+                                    upstreamDns={dashboard.upstreamDns}
+                                    bootstrapDns={dashboard.bootstrapDns}
+                                    allServers={dashboard.allServers}
+                                    setUpstream={this.props.setUpstream}
+                                    testUpstream={this.props.testUpstream}
                                     processingTestUpstream={settings.processingTestUpstream}
-                                    handleUpstreamChange={this.handleUpstreamChange}
-                                    handleUpstreamSubmit={this.handleUpstreamSubmit}
-                                    handleUpstreamTest={this.handleUpstreamTest}
+                                    processingSetUpstream={settings.processingSetUpstream}
                                 />
                                 <Encryption
                                     encryption={this.props.encryption}
@@ -125,7 +110,6 @@ Settings.propTypes = {
     toggleSetting: PropTypes.func,
     handleUpstreamChange: PropTypes.func,
     setUpstream: PropTypes.func,
-    upstream: PropTypes.string,
     t: PropTypes.func,
 };
 
diff --git a/client/src/components/ui/Checkbox.css b/client/src/components/ui/Checkbox.css
index 9d483a5d..0d596a77 100644
--- a/client/src/components/ui/Checkbox.css
+++ b/client/src/components/ui/Checkbox.css
@@ -91,6 +91,10 @@
     line-height: 1.5;
 }
 
+.checkbox__label-text--long {
+    max-width: initial;
+}
+
 .checkbox__label-title {
     display: block;
     line-height: 1.5;
diff --git a/client/src/helpers/form.js b/client/src/helpers/form.js
index 1f0a339a..c9703033 100644
--- a/client/src/helpers/form.js
+++ b/client/src/helpers/form.js
@@ -32,7 +32,7 @@ export const renderSelectField = ({
                 disabled={disabled}
             />
             <span className="checkbox__label">
-                <span className="checkbox__label-text">
+                <span className="checkbox__label-text checkbox__label-text--long">
                     <span className="checkbox__label-title">{placeholder}</span>
                 </span>
             </span>
diff --git a/client/src/helpers/helpers.js b/client/src/helpers/helpers.js
index eb7c7db2..fbfa3b23 100644
--- a/client/src/helpers/helpers.js
+++ b/client/src/helpers/helpers.js
@@ -201,3 +201,5 @@ export const redirectToCurrentProtocol = (values, httpPort = 80) => {
         window.location.replace(`http://${hostname}:${httpPort}/${hash}`);
     }
 };
+
+export const normalizeTextarea = text => text && text.replace(/[;, ]/g, '\n').split('\n').filter(n => n);
diff --git a/client/src/reducers/index.js b/client/src/reducers/index.js
index e83f48a1..90ace4d6 100644
--- a/client/src/reducers/index.js
+++ b/client/src/reducers/index.js
@@ -51,6 +51,8 @@ const dashboard = handleActions({
             dns_address: dnsAddress,
             querylog_enabled: queryLogEnabled,
             upstream_dns: upstreamDns,
+            bootstrap_dns: bootstrapDns,
+            all_servers: allServers,
             protection_enabled: protectionEnabled,
             language,
             http_port: httpPort,
@@ -64,6 +66,8 @@ const dashboard = handleActions({
             dnsAddress,
             queryLogEnabled,
             upstreamDns: upstreamDns.join('\n'),
+            bootstrapDns: bootstrapDns.join('\n'),
+            allServers,
             protectionEnabled,
             language,
             httpPort,
@@ -171,7 +175,9 @@ const dashboard = handleActions({
     logStatusProcessing: false,
     processingVersion: true,
     processingFiltering: true,
-    upstreamDns: [],
+    upstreamDns: '',
+    bootstrapDns: '',
+    allServers: false,
     protectionEnabled: false,
     processingProtection: false,
     httpPort: 80,
diff --git a/config.go b/config.go
index 2f7ce49b..05888888 100644
--- a/config.go
+++ b/config.go
@@ -60,7 +60,8 @@ type dnsConfig struct {
 	UpstreamDNS []string `yaml:"upstream_dns"`
 }
 
-var defaultDNS = []string{"tls://1.1.1.1", "tls://1.0.0.1"}
+var defaultDNS = []string{"https://dns.cloudflare.com/dns-query"}
+var defaultBootstrap = []string{"1.1.1.1"}
 
 type tlsConfigSettings struct {
 	Enabled        bool   `yaml:"enabled" json:"enabled"`                               // Enabled is the encryption (DOT/DOH/HTTPS) status
@@ -114,7 +115,8 @@ var config = configuration{
 			QueryLogEnabled:    true,
 			Ratelimit:          20,
 			RefuseAny:          true,
-			BootstrapDNS:       "8.8.8.8:53",
+			BootstrapDNS:       defaultBootstrap,
+			AllServers:         false,
 		},
 		UpstreamDNS: defaultDNS,
 	},
diff --git a/control.go b/control.go
index 9342aefd..0cd9d504 100644
--- a/control.go
+++ b/control.go
@@ -27,6 +27,8 @@ const updatePeriod = time.Minute * 30
 var versionCheckJSON []byte
 var versionCheckLastTime time.Time
 
+var protocols = []string{"tls://", "https://", "tcp://", "sdns://"}
+
 const versionCheckURL = "https://adguardteam.github.io/AdGuardHome/version.json"
 const versionCheckPeriod = time.Hour * 8
 
@@ -41,9 +43,7 @@ var client = &http.Client{
 func returnOK(w http.ResponseWriter) {
 	_, err := fmt.Fprintf(w, "OK\n")
 	if err != nil {
-		errorText := fmt.Sprintf("Couldn't write body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Couldn't write body: %s", err)
 	}
 }
 
@@ -85,23 +85,20 @@ func handleStatus(w http.ResponseWriter, r *http.Request) {
 		"running":            isRunning(),
 		"bootstrap_dns":      config.DNS.BootstrapDNS,
 		"upstream_dns":       config.DNS.UpstreamDNS,
+		"all_servers":        config.DNS.AllServers,
 		"version":            VersionString,
 		"language":           config.Language,
 	}
 
 	jsonVal, err := json.Marshal(data)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to marshal status json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 500)
+		httpError(w, http.StatusInternalServerError, "Unable to marshal status json: %s", err)
 		return
 	}
 	w.Header().Set("Content-Type", "application/json")
 	_, err = w.Write(jsonVal)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to write response json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 500)
+		httpError(w, http.StatusInternalServerError, "Unable to write response json: %s", err)
 		return
 	}
 }
@@ -139,18 +136,14 @@ func handleQueryLog(w http.ResponseWriter, r *http.Request) {
 
 	jsonVal, err := json.Marshal(data)
 	if err != nil {
-		errorText := fmt.Sprintf("Couldn't marshal data into json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Couldn't marshal data into json: %s", err)
 		return
 	}
 
 	w.Header().Set("Content-Type", "application/json")
 	_, err = w.Write(jsonVal)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to write response json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Unable to write response json: %s", err)
 	}
 }
 
@@ -196,9 +189,7 @@ func handleStatsTop(w http.ResponseWriter, r *http.Request) {
 	w.Header().Set("Content-Type", "application/json")
 	_, err := w.Write(statsJSON.Bytes())
 	if err != nil {
-		errorText := fmt.Sprintf("Couldn't write body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Couldn't write body: %s", err)
 	}
 }
 
@@ -208,9 +199,7 @@ func handleStatsReset(w http.ResponseWriter, r *http.Request) {
 	dnsServer.PurgeStats()
 	_, err := fmt.Fprintf(w, "OK\n")
 	if err != nil {
-		errorText := fmt.Sprintf("Couldn't write body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Couldn't write body: %s", err)
 	}
 }
 
@@ -221,17 +210,13 @@ func handleStats(w http.ResponseWriter, r *http.Request) {
 
 	statsJSON, err := json.Marshal(summed)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to marshal status json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 500)
+		httpError(w, http.StatusInternalServerError, "Unable to marshal status json: %s", err)
 		return
 	}
 	w.Header().Set("Content-Type", "application/json")
 	_, err = w.Write(statsJSON)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to write response json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 500)
+		httpError(w, http.StatusInternalServerError, "Unable to write response json: %s", err)
 		return
 	}
 }
@@ -259,40 +244,31 @@ func handleStatsHistory(w http.ResponseWriter, r *http.Request) {
 	// parse start and end time
 	startTime, err := time.Parse(time.RFC3339, r.URL.Query().Get("start_time"))
 	if err != nil {
-		errorText := fmt.Sprintf("Must specify valid start_time parameter: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusBadRequest)
+		httpError(w, http.StatusBadRequest, "Must specify valid start_time parameter: %s", err)
 		return
 	}
 	endTime, err := time.Parse(time.RFC3339, r.URL.Query().Get("end_time"))
 	if err != nil {
-		errorText := fmt.Sprintf("Must specify valid end_time parameter: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusBadRequest)
+		httpError(w, http.StatusBadRequest, "Must specify valid end_time parameter: %s", err)
 		return
 	}
 
 	data, err := dnsServer.GetStatsHistory(timeUnit, startTime, endTime)
 	if err != nil {
-		errorText := fmt.Sprintf("Cannot get stats history: %s", err)
-		http.Error(w, errorText, http.StatusBadRequest)
+		httpError(w, http.StatusBadRequest, "Cannot get stats history: %s", err)
 		return
 	}
 
 	statsJSON, err := json.Marshal(data)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to marshal status json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Unable to marshal status json: %s", err)
 		return
 	}
 
 	w.Header().Set("Content-Type", "application/json")
 	_, err = w.Write(statsJSON)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to write response json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Unable to write response json: %s", err)
 		return
 	}
 }
@@ -322,68 +298,108 @@ func sortByValue(m map[string]int) []string {
 // upstreams configuration
 // -----------------------
 
-func handleSetUpstreamDNS(w http.ResponseWriter, r *http.Request) {
+// TODO this struct will become unnecessary after config file rework
+type upstreamConfig struct {
+	Upstreams    []string `json:"upstream_dns"`  // Upstreams
+	BootstrapDNS []string `json:"bootstrap_dns"` // Bootstrap DNS
+	AllServers   bool     `json:"all_servers"`   // --all-servers param for dnsproxy
+}
+
+func handleSetUpstreamConfig(w http.ResponseWriter, r *http.Request) {
 	log.Tracef("%s %v", r.Method, r.URL)
-	body, err := ioutil.ReadAll(r.Body)
+	newconfig := upstreamConfig{}
+	err := json.NewDecoder(r.Body).Decode(&newconfig)
 	if err != nil {
-		errorText := fmt.Sprintf("Failed to read request body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusBadRequest)
+		httpError(w, http.StatusBadRequest, "Failed to parse new upstreams config json: %s", err)
 		return
 	}
-	// if empty body -- user is asking for default servers
-	hosts := strings.Fields(string(body))
-
-	if len(hosts) == 0 {
-		config.DNS.UpstreamDNS = defaultDNS
-	} else {
-		config.DNS.UpstreamDNS = hosts
-	}
 
-	err = writeAllConfigs()
-	if err != nil {
-		errorText := fmt.Sprintf("Couldn't write config file: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
-		return
+	for _, u := range newconfig.Upstreams {
+		if err = validateUpstream(u); err != nil {
+			httpError(w, http.StatusBadRequest, "%s can not be used as upstream cause: %s", u, err)
+			return
+		}
 	}
-	err = reconfigureDNSServer()
-	if err != nil {
-		errorText := fmt.Sprintf("Couldn't reconfigure the DNS server: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
-		return
+
+	config.DNS.UpstreamDNS = defaultDNS
+	if len(newconfig.Upstreams) > 0 {
+		config.DNS.UpstreamDNS = newconfig.Upstreams
 	}
-	_, err = fmt.Fprintf(w, "OK %d servers\n", len(hosts))
-	if err != nil {
-		errorText := fmt.Sprintf("Couldn't write body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+
+	// bootstrap servers are plain DNS only.
+	for _, host := range newconfig.BootstrapDNS {
+		if err := checkPlainDNS(host); err != nil {
+			httpError(w, http.StatusBadRequest, "%s can not be used as bootstrap dns cause: %s", host, err)
+			return
+		}
 	}
+
+	config.DNS.BootstrapDNS = defaultBootstrap
+	if len(newconfig.BootstrapDNS) > 0 {
+		config.DNS.BootstrapDNS = newconfig.BootstrapDNS
+	}
+
+	config.DNS.AllServers = newconfig.AllServers
+	httpUpdateConfigReloadDNSReturnOK(w, r)
+}
+
+func validateUpstream(upstream string) error {
+	for _, proto := range protocols {
+		if strings.HasPrefix(upstream, proto) {
+			return nil
+		}
+	}
+
+	if strings.Contains(upstream, "://") {
+		return fmt.Errorf("wrong protocol")
+	}
+
+	return checkPlainDNS(upstream)
+}
+
+// checkPlainDNS checks if host is plain DNS
+func checkPlainDNS(upstream string) error {
+	// Check if host is ip without port
+	if net.ParseIP(upstream) != nil {
+		return nil
+	}
+
+	// Check if host is ip with port
+	ip, port, err := net.SplitHostPort(upstream)
+	if err != nil {
+		return err
+	}
+
+	if net.ParseIP(ip) == nil {
+		return fmt.Errorf("%s is not a valid IP", ip)
+	}
+
+	_, err = strconv.ParseInt(port, 0, 64)
+	if err != nil {
+		return fmt.Errorf("%s is not a valid port: %s", port, err)
+	}
+
+	return nil
 }
 
 func handleTestUpstreamDNS(w http.ResponseWriter, r *http.Request) {
 	log.Tracef("%s %v", r.Method, r.URL)
-	body, err := ioutil.ReadAll(r.Body)
+	upstreamConfig := upstreamConfig{}
+	err := json.NewDecoder(r.Body).Decode(&upstreamConfig)
 	if err != nil {
-		errorText := fmt.Sprintf("Failed to read request body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 400)
+		httpError(w, http.StatusBadRequest, "Failed to read request body: %s", err)
 		return
 	}
-	hosts := strings.Fields(string(body))
 
-	if len(hosts) == 0 {
-		errorText := fmt.Sprintf("No servers specified")
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusBadRequest)
+	if len(upstreamConfig.Upstreams) == 0 {
+		httpError(w, http.StatusBadRequest, "No servers specified")
 		return
 	}
 
 	result := map[string]string{}
 
-	for _, host := range hosts {
-		err = checkDNS(host)
+	for _, host := range upstreamConfig.Upstreams {
+		err = checkDNS(host, upstreamConfig.BootstrapDNS)
 		if err != nil {
 			log.Info("%v", err)
 			result[host] = err.Error()
@@ -394,24 +410,28 @@ func handleTestUpstreamDNS(w http.ResponseWriter, r *http.Request) {
 
 	jsonVal, err := json.Marshal(result)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to marshal status json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Unable to marshal status json: %s", err)
 		return
 	}
 
 	w.Header().Set("Content-Type", "application/json")
 	_, err = w.Write(jsonVal)
 	if err != nil {
-		errorText := fmt.Sprintf("Couldn't write body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Couldn't write body: %s", err)
 	}
 }
 
-func checkDNS(input string) error {
+func checkDNS(input string, bootstrap []string) error {
+	if err := validateUpstream(input); err != nil {
+		return fmt.Errorf("wrong upstream format: %s", err)
+	}
+
+	if len(bootstrap) == 0 {
+		bootstrap = defaultBootstrap
+	}
+
 	log.Debug("Checking if DNS %s works...", input)
-	u, err := upstream.AddressToUpstream(input, upstream.Options{Timeout: dnsforward.DefaultTimeout})
+	u, err := upstream.AddressToUpstream(input, upstream.Options{Bootstrap: bootstrap, Timeout: dnsforward.DefaultTimeout})
 	if err != nil {
 		return fmt.Errorf("failed to choose upstream for %s: %s", input, err)
 	}
@@ -451,9 +471,7 @@ func handleGetVersionJSON(w http.ResponseWriter, r *http.Request) {
 
 	resp, err := client.Get(versionCheckURL)
 	if err != nil {
-		errorText := fmt.Sprintf("Couldn't get version check json from %s: %T %s\n", versionCheckURL, err, err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusBadGateway)
+		httpError(w, http.StatusBadGateway, "Couldn't get version check json from %s: %T %s\n", versionCheckURL, err, err)
 		return
 	}
 	if resp != nil && resp.Body != nil {
@@ -463,18 +481,14 @@ func handleGetVersionJSON(w http.ResponseWriter, r *http.Request) {
 	// read the body entirely
 	body, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
-		errorText := fmt.Sprintf("Couldn't read response body from %s: %s", versionCheckURL, err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusBadGateway)
+		httpError(w, http.StatusBadGateway, "Couldn't read response body from %s: %s", versionCheckURL, err)
 		return
 	}
 
 	w.Header().Set("Content-Type", "application/json")
 	_, err = w.Write(body)
 	if err != nil {
-		errorText := fmt.Sprintf("Couldn't write body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Couldn't write body: %s", err)
 	}
 
 	versionCheckLastTime = now
@@ -510,18 +524,14 @@ func handleFilteringStatus(w http.ResponseWriter, r *http.Request) {
 	config.RUnlock()
 
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to marshal status json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 500)
+		httpError(w, http.StatusInternalServerError, "Unable to marshal status json: %s", err)
 		return
 	}
 
 	w.Header().Set("Content-Type", "application/json")
 	_, err = w.Write(jsonVal)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to write response json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 500)
+		httpError(w, http.StatusInternalServerError, "Unable to write response json: %s", err)
 		return
 	}
 }
@@ -536,21 +546,19 @@ func handleFilteringAddURL(w http.ResponseWriter, r *http.Request) {
 	}
 
 	if len(f.URL) == 0 {
-		http.Error(w, "URL parameter was not specified", 400)
+		http.Error(w, "URL parameter was not specified", http.StatusBadRequest)
 		return
 	}
 
 	if valid := govalidator.IsRequestURL(f.URL); !valid {
-		http.Error(w, "URL parameter is not valid request URL", 400)
+		http.Error(w, "URL parameter is not valid request URL", http.StatusBadRequest)
 		return
 	}
 
 	// Check for duplicates
 	for i := range config.Filters {
 		if config.Filters[i].URL == f.URL {
-			errorText := fmt.Sprintf("Filter URL already added -- %s", f.URL)
-			log.Error(errorText)
-			http.Error(w, errorText, http.StatusBadRequest)
+			httpError(w, http.StatusBadRequest, "Filter URL already added -- %s", f.URL)
 			return
 		}
 	}
@@ -562,30 +570,22 @@ func handleFilteringAddURL(w http.ResponseWriter, r *http.Request) {
 	// Download the filter contents
 	ok, err := f.update(true)
 	if err != nil {
-		errorText := fmt.Sprintf("Couldn't fetch filter from url %s: %s", f.URL, err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusBadRequest)
+		httpError(w, http.StatusBadRequest, "Couldn't fetch filter from url %s: %s", f.URL, err)
 		return
 	}
 	if f.RulesCount == 0 {
-		errorText := fmt.Sprintf("Filter at the url %s has no rules (maybe it points to blank page?)", f.URL)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusBadRequest)
+		httpError(w, http.StatusBadRequest, "Filter at the url %s has no rules (maybe it points to blank page?)", f.URL)
 		return
 	}
 	if !ok {
-		errorText := fmt.Sprintf("Filter at the url %s is invalid (maybe it points to blank page?)", f.URL)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusBadRequest)
+		httpError(w, http.StatusBadRequest, "Filter at the url %s is invalid (maybe it points to blank page?)", f.URL)
 		return
 	}
 
 	// Save the filter contents
 	err = f.save()
 	if err != nil {
-		errorText := fmt.Sprintf("Failed to save filter %d due to %s", f.ID, err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusBadRequest)
+		httpError(w, http.StatusBadRequest, "Failed to save filter %d due to %s", f.ID, err)
 		return
 	}
 
@@ -594,24 +594,18 @@ func handleFilteringAddURL(w http.ResponseWriter, r *http.Request) {
 	config.Filters = append(config.Filters, f)
 	err = writeAllConfigs()
 	if err != nil {
-		errorText := fmt.Sprintf("Couldn't write config file: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Couldn't write config file: %s", err)
 		return
 	}
 
 	err = reconfigureDNSServer()
 	if err != nil {
-		errorText := fmt.Sprintf("Couldn't reconfigure the DNS server: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Couldn't reconfigure the DNS server: %s", err)
 	}
 
 	_, err = fmt.Fprintf(w, "OK %d rules\n", f.RulesCount)
 	if err != nil {
-		errorText := fmt.Sprintf("Couldn't write body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, http.StatusInternalServerError)
+		httpError(w, http.StatusInternalServerError, "Couldn't write body: %s", err)
 	}
 }
 
@@ -619,20 +613,18 @@ func handleFilteringRemoveURL(w http.ResponseWriter, r *http.Request) {
 	log.Tracef("%s %v", r.Method, r.URL)
 	parameters, err := parseParametersFromBody(r.Body)
 	if err != nil {
-		errorText := fmt.Sprintf("failed to parse parameters from body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 400)
+		httpError(w, http.StatusBadRequest, "failed to parse parameters from body: %s", err)
 		return
 	}
 
 	url, ok := parameters["url"]
 	if !ok {
-		http.Error(w, "URL parameter was not specified", 400)
+		http.Error(w, "URL parameter was not specified", http.StatusBadRequest)
 		return
 	}
 
 	if valid := govalidator.IsRequestURL(url); !valid {
-		http.Error(w, "URL parameter is not valid request URL", 400)
+		http.Error(w, "URL parameter is not valid request URL", http.StatusBadRequest)
 		return
 	}
 
@@ -645,8 +637,7 @@ func handleFilteringRemoveURL(w http.ResponseWriter, r *http.Request) {
 			// Remove the filter file
 			err := os.Remove(filter.Path())
 			if err != nil && !os.IsNotExist(err) {
-				errorText := fmt.Sprintf("Couldn't remove the filter file: %s", err)
-				http.Error(w, errorText, http.StatusInternalServerError)
+				httpError(w, http.StatusInternalServerError, "Couldn't remove the filter file: %s", err)
 				return
 			}
 		}
@@ -660,15 +651,13 @@ func handleFilteringEnableURL(w http.ResponseWriter, r *http.Request) {
 	log.Tracef("%s %v", r.Method, r.URL)
 	parameters, err := parseParametersFromBody(r.Body)
 	if err != nil {
-		errorText := fmt.Sprintf("failed to parse parameters from body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 400)
+		httpError(w, http.StatusBadRequest, "failed to parse parameters from body: %s", err)
 		return
 	}
 
 	url, ok := parameters["url"]
 	if !ok {
-		http.Error(w, "URL parameter was not specified", 400)
+		http.Error(w, "URL parameter was not specified", http.StatusBadRequest)
 		return
 	}
 
@@ -700,15 +689,13 @@ func handleFilteringDisableURL(w http.ResponseWriter, r *http.Request) {
 	log.Tracef("%s %v", r.Method, r.URL)
 	parameters, err := parseParametersFromBody(r.Body)
 	if err != nil {
-		errorText := fmt.Sprintf("failed to parse parameters from body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 400)
+		httpError(w, http.StatusBadRequest, "failed to parse parameters from body: %s", err)
 		return
 	}
 
 	url, ok := parameters["url"]
 	if !ok {
-		http.Error(w, "URL parameter was not specified", 400)
+		http.Error(w, "URL parameter was not specified", http.StatusBadRequest)
 		return
 	}
 
@@ -738,9 +725,7 @@ func handleFilteringSetRules(w http.ResponseWriter, r *http.Request) {
 	log.Tracef("%s %v", r.Method, r.URL)
 	body, err := ioutil.ReadAll(r.Body)
 	if err != nil {
-		errorText := fmt.Sprintf("Failed to read request body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 400)
+		httpError(w, http.StatusBadRequest, "Failed to read request body: %s", err)
 		return
 	}
 
@@ -778,17 +763,13 @@ func handleSafeBrowsingStatus(w http.ResponseWriter, r *http.Request) {
 	}
 	jsonVal, err := json.Marshal(data)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to marshal status json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 500)
+		httpError(w, http.StatusInternalServerError, "Unable to marshal status json: %s", err)
 	}
 
 	w.Header().Set("Content-Type", "application/json")
 	_, err = w.Write(jsonVal)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to write response json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 500)
+		httpError(w, http.StatusInternalServerError, "Unable to write response json: %s", err)
 		return
 	}
 }
@@ -800,9 +781,7 @@ func handleParentalEnable(w http.ResponseWriter, r *http.Request) {
 	log.Tracef("%s %v", r.Method, r.URL)
 	parameters, err := parseParametersFromBody(r.Body)
 	if err != nil {
-		errorText := fmt.Sprintf("failed to parse parameters from body: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 400)
+		httpError(w, http.StatusBadRequest, "failed to parse parameters from body: %s", err)
 		return
 	}
 
@@ -859,18 +838,14 @@ func handleParentalStatus(w http.ResponseWriter, r *http.Request) {
 	}
 	jsonVal, err := json.Marshal(data)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to marshal status json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 500)
+		httpError(w, http.StatusInternalServerError, "Unable to marshal status json: %s", err)
 		return
 	}
 
 	w.Header().Set("Content-Type", "application/json")
 	_, err = w.Write(jsonVal)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to write response json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 500)
+		httpError(w, http.StatusInternalServerError, "Unable to write response json: %s", err)
 		return
 	}
 }
@@ -898,18 +873,14 @@ func handleSafeSearchStatus(w http.ResponseWriter, r *http.Request) {
 	}
 	jsonVal, err := json.Marshal(data)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to marshal status json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 500)
+		httpError(w, http.StatusInternalServerError, "Unable to marshal status json: %s", err)
 		return
 	}
 
 	w.Header().Set("Content-Type", "application/json")
 	_, err = w.Write(jsonVal)
 	if err != nil {
-		errorText := fmt.Sprintf("Unable to write response json: %s", err)
-		log.Error(errorText)
-		http.Error(w, errorText, 500)
+		httpError(w, http.StatusInternalServerError, "Unable to write response json: %s", err)
 		return
 	}
 }
@@ -1053,7 +1024,7 @@ func registerControlHandlers() {
 	http.HandleFunc("/control/querylog", postInstall(optionalAuth(ensureGET(handleQueryLog))))
 	http.HandleFunc("/control/querylog_enable", postInstall(optionalAuth(ensurePOST(handleQueryLogEnable))))
 	http.HandleFunc("/control/querylog_disable", postInstall(optionalAuth(ensurePOST(handleQueryLogDisable))))
-	http.HandleFunc("/control/set_upstream_dns", postInstall(optionalAuth(ensurePOST(handleSetUpstreamDNS))))
+	http.HandleFunc("/control/set_upstreams_config", postInstall(optionalAuth(ensurePOST(handleSetUpstreamConfig))))
 	http.HandleFunc("/control/test_upstream_dns", postInstall(optionalAuth(ensurePOST(handleTestUpstreamDNS))))
 	http.HandleFunc("/control/i18n/change_language", postInstall(optionalAuth(ensurePOST(handleI18nChangeLanguage))))
 	http.HandleFunc("/control/i18n/current_language", postInstall(optionalAuth(ensureGET(handleI18nCurrentLanguage))))
diff --git a/dns.go b/dns.go
index 8cf5c40d..56fae956 100644
--- a/dns.go
+++ b/dns.go
@@ -61,7 +61,7 @@ func generateServerConfig() dnsforward.ServerConfig {
 	for _, u := range config.DNS.UpstreamDNS {
 		opts := upstream.Options{
 			Timeout:   dnsforward.DefaultTimeout,
-			Bootstrap: []string{config.DNS.BootstrapDNS},
+			Bootstrap: config.DNS.BootstrapDNS,
 		}
 		dnsUpstream, err := upstream.AddressToUpstream(u, opts)
 		if err != nil {
@@ -71,6 +71,7 @@ func generateServerConfig() dnsforward.ServerConfig {
 		}
 		newconfig.Upstreams = append(newconfig.Upstreams, dnsUpstream)
 	}
+	newconfig.AllServers = config.DNS.AllServers
 	return newconfig
 }
 
diff --git a/dnsfilter/dnsfilter.go b/dnsfilter/dnsfilter.go
index 561ccb04..b33465f9 100644
--- a/dnsfilter/dnsfilter.go
+++ b/dnsfilter/dnsfilter.go
@@ -16,8 +16,8 @@ import (
 	"sync/atomic"
 	"time"
 
-	"github.com/bluele/gcache"
 	"github.com/AdguardTeam/golibs/log"
+	"github.com/bluele/gcache"
 	"golang.org/x/net/publicsuffix"
 )
 
diff --git a/dnsforward/dnsforward.go b/dnsforward/dnsforward.go
index 26f7dfb4..7b8430ed 100644
--- a/dnsforward/dnsforward.go
+++ b/dnsforward/dnsforward.go
@@ -62,11 +62,12 @@ type FilteringConfig struct {
 	ProtectionEnabled  bool     `yaml:"protection_enabled"`   // whether or not use any of dnsfilter features
 	FilteringEnabled   bool     `yaml:"filtering_enabled"`    // whether or not use filter lists
 	BlockedResponseTTL uint32   `yaml:"blocked_response_ttl"` // if 0, then default is used (3600)
-	QueryLogEnabled    bool     `yaml:"querylog_enabled"`
-	Ratelimit          int      `yaml:"ratelimit"`
-	RatelimitWhitelist []string `yaml:"ratelimit_whitelist"`
-	RefuseAny          bool     `yaml:"refuse_any"`
-	BootstrapDNS       string   `yaml:"bootstrap_dns"`
+	QueryLogEnabled    bool     `yaml:"querylog_enabled"`     // if true, query log is enabled
+	Ratelimit          int      `yaml:"ratelimit"`            // max number of requests per second from a given IP (0 to disable)
+	RatelimitWhitelist []string `yaml:"ratelimit_whitelist"`  // a list of whitelisted client IP addresses
+	RefuseAny          bool     `yaml:"refuse_any"`           // if true, refuse ANY requests
+	BootstrapDNS       []string `yaml:"bootstrap_dns"`        // a list of bootstrap DNS for DoH and DoT (plain DNS only)
+	AllServers         bool     `yaml:"all_servers"`          // if true, parallel queries to all configured upstream servers are enabled
 
 	dnsfilter.Config `yaml:",inline"`
 }
@@ -163,6 +164,7 @@ func (s *Server) startInternal(config *ServerConfig) error {
 		CacheEnabled:       true,
 		Upstreams:          s.Upstreams,
 		Handler:            s.handleDNSRequest,
+		AllServers:         s.AllServers,
 	}
 
 	if s.TLSListenAddr != nil && s.CertificateChain != "" && s.PrivateKey != "" {
diff --git a/openapi/openapi.yaml b/openapi/openapi.yaml
index 4cf406e0..d8b1072c 100644
--- a/openapi/openapi.yaml
+++ b/openapi/openapi.yaml
@@ -87,26 +87,21 @@ paths:
                 200:
                     description: OK
 
-    /set_upstream_dns:
+    /set_upstreams_config:
         post:
             tags:
                 - global
-            operationId: setUpstreamDNS
-            summary: 'Set upstream DNS for coredns, empty value will reset it to default values'
+            operationId: setUpstreamsConfig
+            summary: "Updates the current upstreams configuration"
             consumes:
-                - text/plain
+                - application/json
             parameters:
-                -   in: body
-                    name: upstream
-                    description: 'Upstream servers, separated by newline or space, port is optional after colon'
-                    schema:
-                        # TODO: use JSON
-                        type: string
-                        example: |
-                            1.1.1.1
-                            1.0.0.1
-                            8.8.8.8 8.8.4.4
-                            192.168.1.104:53535
+                - in: "body"
+                  name: "body"
+                  description: "Upstreams configuration JSON"
+                  required: true
+                  schema:
+                      $ref: "#/definitions/UpstreamsConfig"
             responses:
                 200:
                     description: OK
@@ -116,21 +111,15 @@ paths:
             tags:
                 - global
             operationId: testUpstreamDNS
-            summary: 'Test upstream DNS'
+            summary: "Test upstream configuration"
             consumes:
-                - text/plain
+                - application/json
             parameters:
-                -   in: body
-                    name: upstream
-                    description: 'Upstream servers, separated by newline or space, port is optional after colon'
+                -   in: "body"
+                    name: "body"
+                    description: "Upstream configuration to be tested"
                     schema:
-                        # TODO: use JSON
-                        type: string
-                        example: |
-                            1.1.1.1
-                            1.0.0.1
-                            8.8.8.8 8.8.4.4
-                            192.168.1.104:53535
+                        $ref: "#/definitions/UpstreamsConfig"
             responses:
                 200:
                     description: 'Status of testing each requested server, with "OK" meaning that server works, any other text means an error.'
@@ -798,6 +787,33 @@ definitions:
             language:
                 type: "string"
                 example: "en"
+    UpstreamsConfig:
+        type: "object"
+        description: "Upstreams configuration"
+        required:
+            - "bootstrap_dns"
+            - "upstream_dns"
+            - "all_servers"
+        properties:
+            bootstrap_dns:
+                type: "array"
+                description: 'Bootstrap servers, port is optional after colon. Empty value will reset it to default values'
+                items:
+                    type: "string"
+                example:
+                    - "8.8.8.8:53"
+                    - "1.1.1.1:53"
+            upstream_dns:
+                type: "array"
+                description: 'Upstream servers, port is optional after colon. Empty value will reset it to default values'
+                items:
+                    type: "string"
+                example:
+                    - "tls://1.1.1.1"
+                    - "tls://1.0.0.1"
+            all_servers:
+                type: "boolean"
+                description: "If true, parallel queries to all configured upstream servers are enabled"
     Filter:
         type: "object"
         description: "Filter subscription info"
diff --git a/upgrade.go b/upgrade.go
index c988700a..0c9aeca7 100644
--- a/upgrade.go
+++ b/upgrade.go
@@ -10,7 +10,7 @@ import (
 	yaml "gopkg.in/yaml.v2"
 )
 
-const currentSchemaVersion = 2 // used for upgrading from old configs to new config
+const currentSchemaVersion = 3 // used for upgrading from old configs to new config
 
 // Performs necessary upgrade operations if needed
 func upgradeConfig() error {
@@ -59,12 +59,17 @@ func upgradeConfig() error {
 func upgradeConfigSchema(oldVersion int, diskConfig *map[string]interface{}) error {
 	switch oldVersion {
 	case 0:
-		err := upgradeSchema0to2(diskConfig)
+		err := upgradeSchema0to3(diskConfig)
 		if err != nil {
 			return err
 		}
 	case 1:
-		err := upgradeSchema1to2(diskConfig)
+		err := upgradeSchema1to3(diskConfig)
+		if err != nil {
+			return err
+		}
+	case 2:
+		err := upgradeSchema2to3(diskConfig)
 		if err != nil {
 			return err
 		}
@@ -135,12 +140,60 @@ func upgradeSchema1to2(diskConfig *map[string]interface{}) error {
 	return nil
 }
 
-// jump two schemas at once -- this time we just do it sequentially
-func upgradeSchema0to2(diskConfig *map[string]interface{}) error {
+// Third schema upgrade:
+// Bootstrap DNS becomes an array
+func upgradeSchema2to3(diskConfig *map[string]interface{}) error {
+	log.Printf("%s(): called", _Func())
+
+	// Let's read dns configuration from diskConfig
+	dnsConfig, ok := (*diskConfig)["dns"]
+	if !ok {
+		return fmt.Errorf("no DNS configuration in config file")
+	}
+
+	// Convert interface{} to map[string]interface{}
+	newDNSConfig := make(map[string]interface{})
+
+	switch v := dnsConfig.(type) {
+	case map[interface{}]interface{}:
+		for k, v := range v {
+			newDNSConfig[fmt.Sprint(k)] = v
+		}
+	default:
+		return fmt.Errorf("DNS configuration is not a map")
+	}
+
+	// Replace bootstrap_dns value filed with new array contains old bootstrap_dns inside
+	if bootstrapDNS, ok := (newDNSConfig)["bootstrap_dns"]; ok {
+		newBootstrapConfig := []string{fmt.Sprint(bootstrapDNS)}
+		(newDNSConfig)["bootstrap_dns"] = newBootstrapConfig
+		(*diskConfig)["dns"] = newDNSConfig
+	} else {
+		return fmt.Errorf("no bootstrap DNS in DNS config")
+	}
+
+	// Bump schema version
+	(*diskConfig)["schema_version"] = 3
+
+	return nil
+}
+
+// jump three schemas at once -- this time we just do it sequentially
+func upgradeSchema0to3(diskConfig *map[string]interface{}) error {
 	err := upgradeSchema0to1(diskConfig)
 	if err != nil {
 		return err
 	}
 
-	return upgradeSchema1to2(diskConfig)
+	return upgradeSchema1to3(diskConfig)
+}
+
+// jump two schemas at once -- this time we just do it sequentially
+func upgradeSchema1to3(diskConfig *map[string]interface{}) error {
+	err := upgradeSchema1to2(diskConfig)
+	if err != nil {
+		return err
+	}
+
+	return upgradeSchema2to3(diskConfig)
 }
diff --git a/upgrade_test.go b/upgrade_test.go
new file mode 100644
index 00000000..8980eda9
--- /dev/null
+++ b/upgrade_test.go
@@ -0,0 +1,230 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestUpgrade1to2(t *testing.T) {
+	// let's create test config for 1 schema version
+	diskConfig := createTestDiskConfig(1)
+
+	// update config
+	err := upgradeSchema1to2(&diskConfig)
+	if err != nil {
+		t.Fatalf("Can't upgrade schema version from 1 to 2")
+	}
+
+	// ensure that schema version was bumped
+	compareSchemaVersion(t, diskConfig["schema_version"], 2)
+
+	// old coredns entry should be removed
+	_, ok := diskConfig["coredns"]
+	if ok {
+		t.Fatalf("Core DNS config was not removed after upgrade schema version from 1 to 2")
+	}
+
+	// pull out new dns config
+	dnsMap, ok := diskConfig["dns"]
+	if !ok {
+		t.Fatalf("No DNS config after upgrade schema version from 1 to 2")
+	}
+
+	// cast dns configurations to maps and compare them
+	oldDNSConfig := castInterfaceToMap(t, createTestDNSConfig(1))
+	newDNSConfig := castInterfaceToMap(t, dnsMap)
+	compareConfigs(t, &oldDNSConfig, &newDNSConfig)
+
+	// exclude dns config and schema version from disk config comparison
+	oldExcludedEntries := []string{"coredns", "schema_version"}
+	newExcludedEntries := []string{"dns", "schema_version"}
+	oldDiskConfig := createTestDiskConfig(1)
+	compareConfigsWithoutEntries(t, &oldDiskConfig, &diskConfig, oldExcludedEntries, newExcludedEntries)
+}
+
+func TestUpgrade2to3(t *testing.T) {
+	// let's create test config
+	diskConfig := createTestDiskConfig(2)
+
+	// upgrade schema from 2 to 3
+	err := upgradeSchema2to3(&diskConfig)
+	if err != nil {
+		t.Fatalf("Can't update schema version from 2 to 3: %s", err)
+	}
+
+	// check new schema version
+	compareSchemaVersion(t, diskConfig["schema_version"], 3)
+
+	// pull out new dns configuration
+	dnsMap, ok := diskConfig["dns"]
+	if !ok {
+		t.Fatalf("No dns config in new configuration")
+	}
+
+	// cast dns configuration to map
+	newDNSConfig := castInterfaceToMap(t, dnsMap)
+
+	// check if bootstrap DNS becomes an array
+	bootstrapDNS := newDNSConfig["bootstrap_dns"]
+	switch v := bootstrapDNS.(type) {
+	case []string:
+		if len(v) != 1 {
+			t.Fatalf("Wrong count of bootsrap DNS servers: %d", len(v))
+		}
+
+		if v[0] != "8.8.8.8:53" {
+			t.Fatalf("Bootsrap DNS server is not 8.8.8.8:53 : %s", v[0])
+		}
+	default:
+		t.Fatalf("Wrong type for bootsrap DNS: %T", v)
+	}
+
+	// exclude bootstrap DNS from DNS configs comparison
+	excludedEntries := []string{"bootstrap_dns"}
+	oldDNSConfig := castInterfaceToMap(t, createTestDNSConfig(2))
+	compareConfigsWithoutEntries(t, &oldDNSConfig, &newDNSConfig, excludedEntries, excludedEntries)
+
+	// excluded dns config and schema version from disk config comparison
+	excludedEntries = []string{"dns", "schema_version"}
+	oldDiskConfig := createTestDiskConfig(2)
+	compareConfigsWithoutEntries(t, &oldDiskConfig, &diskConfig, excludedEntries, excludedEntries)
+}
+
+func castInterfaceToMap(t *testing.T, oldConfig interface{}) (newConfig map[string]interface{}) {
+	newConfig = make(map[string]interface{})
+	switch v := oldConfig.(type) {
+	case map[interface{}]interface{}:
+		for key, value := range v {
+			newConfig[fmt.Sprint(key)] = value
+		}
+	case map[string]interface{}:
+		for key, value := range v {
+			newConfig[key] = value
+		}
+	default:
+		t.Fatalf("DNS configuration is not a map")
+	}
+	return
+}
+
+// compareConfigsWithoutEntry removes entries from configs and returns result of compareConfigs
+func compareConfigsWithoutEntries(t *testing.T, oldConfig, newConfig *map[string]interface{}, oldKey, newKey []string) {
+	for _, k := range oldKey {
+		delete(*oldConfig, k)
+	}
+	for _, k := range newKey {
+		delete(*newConfig, k)
+	}
+	compareConfigs(t, oldConfig, newConfig)
+}
+
+// compares configs before and after schema upgrade
+func compareConfigs(t *testing.T, oldConfig, newConfig *map[string]interface{}) {
+	if len(*oldConfig) != len(*newConfig) {
+		t.Fatalf("wrong config entries count! Before upgrade: %d; After upgrade: %d", len(*oldConfig), len(*oldConfig))
+	}
+
+	// Check old and new entries
+	for k, v := range *newConfig {
+		switch value := v.(type) {
+		case string:
+			if value != (*oldConfig)[k] {
+				t.Fatalf("wrong value for string %s. Before update: %s; After update: %s", k, (*oldConfig)[k], value)
+			}
+		case int:
+			if value != (*oldConfig)[k] {
+				t.Fatalf("wrong value for int %s. Before update: %d; After update: %d", k, (*oldConfig)[k], value)
+			}
+		case []string:
+			for i, line := range value {
+				if len((*oldConfig)[k].([]string)) != len(value) {
+					t.Fatalf("wrong array length for %s. Before update: %d; After update: %d", k, len((*oldConfig)[k].([]string)), len(value))
+				}
+				if (*oldConfig)[k].([]string)[i] != line {
+					t.Fatalf("wrong data for string array %s. Before update: %s; After update: %s", k, (*oldConfig)[k].([]string)[i], line)
+				}
+			}
+		case bool:
+			if v != (*oldConfig)[k].(bool) {
+				t.Fatalf("wrong boolean value for %s", k)
+			}
+		case []filter:
+			if len((*oldConfig)[k].([]filter)) != len(value) {
+				t.Fatalf("wrong filters count. Before update: %d; After update: %d", len((*oldConfig)[k].([]filter)), len(value))
+			}
+			for i, newFilter := range value {
+				oldFilter := (*oldConfig)[k].([]filter)[i]
+				if oldFilter.Enabled != newFilter.Enabled || oldFilter.Name != newFilter.Name || oldFilter.RulesCount != newFilter.RulesCount {
+					t.Fatalf("old filter %s not equals new filter %s", oldFilter.Name, newFilter.Name)
+				}
+			}
+		default:
+			t.Fatalf("uknown data type for %s: %T", k, value)
+		}
+	}
+}
+
+// compareSchemaVersion check if newSchemaVersion equals schemaVersion
+func compareSchemaVersion(t *testing.T, newSchemaVersion interface{}, schemaVersion int) {
+	switch v := newSchemaVersion.(type) {
+	case int:
+		if v != schemaVersion {
+			t.Fatalf("Wrong schema version in new config file")
+		}
+	default:
+		t.Fatalf("Schema version is not an integer after update")
+	}
+}
+
+func createTestDiskConfig(schemaVersion int) (diskConfig map[string]interface{}) {
+	diskConfig = make(map[string]interface{})
+	diskConfig["language"] = "en"
+	diskConfig["filters"] = []filter{
+		{
+			URL:        "https://filters.adtidy.org/android/filters/111_optimized.txt",
+			Name:       "Latvian filter",
+			RulesCount: 100,
+		},
+		{
+			URL:        "https://easylist.to/easylistgermany/easylistgermany.txt",
+			Name:       "Germany filter",
+			RulesCount: 200,
+		},
+	}
+	diskConfig["user_rules"] = []string{}
+	diskConfig["schema_version"] = schemaVersion
+	diskConfig["bind_host"] = "0.0.0.0"
+	diskConfig["bind_port"] = 80
+	diskConfig["auth_name"] = "name"
+	diskConfig["auth_pass"] = "pass"
+	dnsConfig := createTestDNSConfig(schemaVersion)
+	if schemaVersion > 1 {
+		diskConfig["dns"] = dnsConfig
+	} else {
+		diskConfig["coredns"] = dnsConfig
+	}
+	return diskConfig
+}
+
+func createTestDNSConfig(schemaVersion int) map[interface{}]interface{} {
+	dnsConfig := make(map[interface{}]interface{})
+	dnsConfig["port"] = 53
+	dnsConfig["blocked_response_ttl"] = 10
+	dnsConfig["querylog_enabled"] = true
+	dnsConfig["ratelimit"] = 20
+	dnsConfig["bootstrap_dns"] = "8.8.8.8:53"
+	if schemaVersion > 2 {
+		dnsConfig["bootstrap_dns"] = []string{"8.8.8.8:53"}
+	}
+	dnsConfig["parental_sensitivity"] = 13
+	dnsConfig["ratelimit_whitelist"] = []string{}
+	dnsConfig["upstream_dns"] = []string{"tls://1.1.1.1", "tls://1.0.0.1", "8.8.8.8"}
+	dnsConfig["filtering_enabled"] = true
+	dnsConfig["refuse_any"] = true
+	dnsConfig["parental_enabled"] = true
+	dnsConfig["bind_host"] = "0.0.0.0"
+	dnsConfig["protection_enabled"] = true
+	dnsConfig["safesearch_enabled"] = true
+	dnsConfig["safebrowsing_enabled"] = true
+	return dnsConfig
+}