diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4bd11cc1..0903fdbf 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,11 +10,12 @@ and this project adheres to
 ## [Unreleased]
 
 <!--
-## [v0.107.0] - 2021-06-28 (APPROX.)
+## [v0.107.0] - 2021-08-03 (APPROX.)
 -->
 
 ### Added
 
+- Optimistic cache ([#2145]).
 - New possible value of `6h` for `querylog_interval` setting ([#2504]).
 - Blocking access using client IDs ([#2624], [#3162]).
 - `source` directives support in `/etc/network/interfaces` on Linux ([#3257]).
@@ -53,11 +54,6 @@ and this project adheres to
 
 ### Deprecated
 
-<!--
-TODO(a.garipov): Remove the Go 1.16 deprecation message if Go 1.17 is not
-released by then.
--->
-
 - Go 1.16 support.  v0.108.0 will require at least Go 1.17 to build.
 
 ### Fixed
@@ -83,6 +79,7 @@ released by then.
 [#1381]: https://github.com/AdguardTeam/AdGuardHome/issues/1381
 [#1691]: https://github.com/AdguardTeam/AdGuardHome/issues/1691
 [#2141]: https://github.com/AdguardTeam/AdGuardHome/issues/2141
+[#2145]: https://github.com/AdguardTeam/AdGuardHome/issues/2145
 [#2280]: https://github.com/AdguardTeam/AdGuardHome/issues/2280
 [#2439]: https://github.com/AdguardTeam/AdGuardHome/issues/2439
 [#2441]: https://github.com/AdguardTeam/AdGuardHome/issues/2441
diff --git a/client/src/__locales/en.json b/client/src/__locales/en.json
index 8254c9ea..246f19c7 100644
--- a/client/src/__locales/en.json
+++ b/client/src/__locales/en.json
@@ -597,6 +597,8 @@
     "cache_ttl_min_override_desc": "Extend short time-to-live values (seconds) received from the upstream server when caching DNS responses",
     "cache_ttl_max_override_desc": "Set a maximum time-to-live value (seconds) for entries in the DNS cache",
     "ttl_cache_validation": "Minimum cache TTL value must be less than or equal to the maximum value",
+    "cache_optimistic": "Optimistic",
+    "cache_optimistic_desc": "Make AdGuard Home respond from the cache even when the entries are expired and also try to refresh them.",
     "filter_category_general": "General",
     "filter_category_security": "Security",
     "filter_category_regional": "Regional",
diff --git a/client/src/components/Settings/Dns/Cache/Form.js b/client/src/components/Settings/Dns/Cache/Form.js
index 9a13ec63..5b0fe6a2 100644
--- a/client/src/components/Settings/Dns/Cache/Form.js
+++ b/client/src/components/Settings/Dns/Cache/Form.js
@@ -3,7 +3,7 @@ import PropTypes from 'prop-types';
 import { Field, reduxForm } from 'redux-form';
 import { Trans, useTranslation } from 'react-i18next';
 import { shallowEqual, useSelector } from 'react-redux';
-import { renderInputField, toNumber } from '../../../../helpers/form';
+import { renderInputField, toNumber, CheckboxField } from '../../../../helpers/form';
 import { CACHE_CONFIG_FIELDS, FORM_NAME, UINT32_RANGE } from '../../../../helpers/constants';
 import { replaceZeroWithEmptyString } from '../../../../helpers/helpers';
 
@@ -47,27 +47,48 @@ const Form = ({
             }) => <div className="col-12" key={name}>
                     <div className="col-12 col-md-7 p-0">
                         <div className="form__group form__group--settings">
-                            <label htmlFor={name}
-                                   className="form__label form__label--with-desc">{t(title)}</label>
+                            <label
+                                htmlFor={name}
+                                className="form__label form__label--with-desc"
+                            >
+                                {t(title)}
+                            </label>
                             <div className="form__desc form__desc--top">{t(description)}</div>
                             <Field
-                                    name={name}
-                                    type="number"
-                                    component={renderInputField}
-                                    placeholder={t(placeholder)}
-                                    disabled={processingSetConfig}
-                                    className="form-control"
-                                    validate={validate}
-                                    normalizeOnBlur={replaceZeroWithEmptyString}
-                                    normalize={toNumber}
-                                    min={min}
-                                    max={max}
+                                name={name}
+                                type="number"
+                                component={renderInputField}
+                                placeholder={t(placeholder)}
+                                disabled={processingSetConfig}
+                                className="form-control"
+                                validate={validate}
+                                normalizeOnBlur={replaceZeroWithEmptyString}
+                                normalize={toNumber}
+                                min={min}
+                                max={max}
                             />
                         </div>
                     </div>
                 </div>)}
-            {minExceedsMax
-            && <span className="text-danger pl-3 pb-3">{t('ttl_cache_validation')}</span>}
+            {minExceedsMax && (
+                <span className="text-danger pl-3 pb-3">
+                    {t('ttl_cache_validation')}
+                </span>
+            )}
+        </div>
+        <div className="row">
+            <div className="col-12 col-md-7">
+                <div className="form__group form__group--settings">
+                    <Field
+                        name="cache_optimistic"
+                        type="checkbox"
+                        component={CheckboxField}
+                        placeholder={t('cache_optimistic')}
+                        disabled={processingSetConfig}
+                        subtitle={t('cache_optimistic_desc')}
+                    />
+                </div>
+            </div>
         </div>
         <button
             type="submit"
diff --git a/client/src/components/Settings/Dns/Cache/index.js b/client/src/components/Settings/Dns/Cache/index.js
index 2c70406b..3e137229 100644
--- a/client/src/components/Settings/Dns/Cache/index.js
+++ b/client/src/components/Settings/Dns/Cache/index.js
@@ -10,7 +10,7 @@ const CacheConfig = () => {
     const { t } = useTranslation();
     const dispatch = useDispatch();
     const {
-        cache_size, cache_ttl_max, cache_ttl_min,
+        cache_size, cache_ttl_max, cache_ttl_min, cache_optimistic,
     } = useSelector((state) => state.dnsConfig, shallowEqual);
 
     const handleFormSubmit = (values) => {
@@ -31,6 +31,7 @@ const CacheConfig = () => {
                         cache_size: replaceZeroWithEmptyString(cache_size),
                         cache_ttl_max: replaceZeroWithEmptyString(cache_ttl_max),
                         cache_ttl_min: replaceZeroWithEmptyString(cache_ttl_min),
+                        cache_optimistic,
                     }}
                     onSubmit={handleFormSubmit}
                 />
diff --git a/internal/dnsforward/config.go b/internal/dnsforward/config.go
index 213f6221..5a7c81d7 100644
--- a/internal/dnsforward/config.go
+++ b/internal/dnsforward/config.go
@@ -101,6 +101,8 @@ type FilteringConfig struct {
 	CacheSize   uint32 `yaml:"cache_size"`    // DNS cache size (in bytes)
 	CacheMinTTL uint32 `yaml:"cache_ttl_min"` // override TTL value (minimum) received from upstream server
 	CacheMaxTTL uint32 `yaml:"cache_ttl_max"` // override TTL value (maximum) received from upstream server
+	// CacheOptimistic defines if optimistic cache mechanism should be used.
+	CacheOptimistic bool `yaml:"cache_optimistic"`
 
 	// Other settings
 	// --
@@ -210,6 +212,7 @@ func (s *Server) createProxyConfig() (proxy.Config, error) {
 		RefuseAny:              s.conf.RefuseAny,
 		CacheMinTTL:            s.conf.CacheMinTTL,
 		CacheMaxTTL:            s.conf.CacheMaxTTL,
+		CacheOptimistic:        s.conf.CacheOptimistic,
 		UpstreamConfig:         s.conf.UpstreamConfig,
 		BeforeRequestHandler:   s.beforeRequestHandler,
 		RequestHandler:         s.handleDNSRequest,
diff --git a/internal/dnsforward/http.go b/internal/dnsforward/http.go
index 3f2ccf55..f72af780 100644
--- a/internal/dnsforward/http.go
+++ b/internal/dnsforward/http.go
@@ -41,6 +41,7 @@ type dnsConfig struct {
 	CacheSize         *uint32       `json:"cache_size"`
 	CacheMinTTL       *uint32       `json:"cache_ttl_min"`
 	CacheMaxTTL       *uint32       `json:"cache_ttl_max"`
+	CacheOptimistic   *bool         `json:"cache_optimistic"`
 	ResolveClients    *bool         `json:"resolve_clients"`
 	UsePrivateRDNS    *bool         `json:"use_private_ptr_resolvers"`
 	LocalPTRUpstreams *[]string     `json:"local_ptr_upstreams"`
@@ -64,6 +65,7 @@ func (s *Server) getDNSConfig() dnsConfig {
 	cacheSize := s.conf.CacheSize
 	cacheMinTTL := s.conf.CacheMinTTL
 	cacheMaxTTL := s.conf.CacheMaxTTL
+	cacheOptimistic := s.conf.CacheOptimistic
 	resolveClients := s.conf.ResolveClients
 	usePrivateRDNS := s.conf.UsePrivateRDNS
 	localPTRUpstreams := aghstrings.CloneSliceOrEmpty(s.conf.LocalPTRResolvers)
@@ -89,6 +91,7 @@ func (s *Server) getDNSConfig() dnsConfig {
 		CacheSize:         &cacheSize,
 		CacheMinTTL:       &cacheMinTTL,
 		CacheMaxTTL:       &cacheMaxTTL,
+		CacheOptimistic:   &cacheOptimistic,
 		UpstreamMode:      &upstreamMode,
 		ResolveClients:    &resolveClients,
 		UsePrivateRDNS:    &usePrivateRDNS,
@@ -283,6 +286,11 @@ func (s *Server) setConfigRestartable(dc dnsConfig) (restart bool) {
 		restart = true
 	}
 
+	if dc.CacheOptimistic != nil {
+		s.conf.CacheOptimistic = *dc.CacheOptimistic
+		restart = true
+	}
+
 	return restart
 }
 
diff --git a/internal/dnsforward/http_test.go b/internal/dnsforward/http_test.go
index 99fece08..582317ec 100644
--- a/internal/dnsforward/http_test.go
+++ b/internal/dnsforward/http_test.go
@@ -48,7 +48,7 @@ func loadTestData(t *testing.T, casesFileName string, cases interface{}) {
 
 const jsonExt = ".json"
 
-func TestDNSForwardHTTTP_handleGetConfig(t *testing.T) {
+func TestDNSForwardHTTP_handleGetConfig(t *testing.T) {
 	filterConf := &filtering.Config{
 		SafeBrowsingEnabled:   true,
 		SafeBrowsingCacheSize: 1000,
@@ -123,7 +123,7 @@ func TestDNSForwardHTTTP_handleGetConfig(t *testing.T) {
 	}
 }
 
-func TestDNSForwardHTTTP_handleSetConfig(t *testing.T) {
+func TestDNSForwardHTTP_handleSetConfig(t *testing.T) {
 	filterConf := &filtering.Config{
 		SafeBrowsingEnabled:   true,
 		SafeBrowsingCacheSize: 1000,
diff --git a/internal/dnsforward/testdata/TestDNSForwardHTTTP_handleGetConfig.json b/internal/dnsforward/testdata/TestDNSForwardHTTP_handleGetConfig.json
similarity index 95%
rename from internal/dnsforward/testdata/TestDNSForwardHTTTP_handleGetConfig.json
rename to internal/dnsforward/testdata/TestDNSForwardHTTP_handleGetConfig.json
index 4d810c94..538865c5 100644
--- a/internal/dnsforward/testdata/TestDNSForwardHTTTP_handleGetConfig.json
+++ b/internal/dnsforward/testdata/TestDNSForwardHTTP_handleGetConfig.json
@@ -23,6 +23,7 @@
     "cache_size": 0,
     "cache_ttl_min": 0,
     "cache_ttl_max": 0,
+    "cache_optimistic": false,
     "resolve_clients": false,
     "use_private_ptr_resolvers": false,
     "local_ptr_upstreams": []
@@ -51,6 +52,7 @@
     "cache_size": 0,
     "cache_ttl_min": 0,
     "cache_ttl_max": 0,
+    "cache_optimistic": false,
     "resolve_clients": false,
     "use_private_ptr_resolvers": false,
     "local_ptr_upstreams": []
@@ -79,6 +81,7 @@
     "cache_size": 0,
     "cache_ttl_min": 0,
     "cache_ttl_max": 0,
+    "cache_optimistic": false,
     "resolve_clients": false,
     "use_private_ptr_resolvers": false,
     "local_ptr_upstreams": []
diff --git a/internal/dnsforward/testdata/TestDNSForwardHTTTP_handleSetConfig.json b/internal/dnsforward/testdata/TestDNSForwardHTTP_handleSetConfig.json
similarity index 95%
rename from internal/dnsforward/testdata/TestDNSForwardHTTTP_handleSetConfig.json
rename to internal/dnsforward/testdata/TestDNSForwardHTTP_handleSetConfig.json
index 2d2e34b5..b594029c 100644
--- a/internal/dnsforward/testdata/TestDNSForwardHTTTP_handleSetConfig.json
+++ b/internal/dnsforward/testdata/TestDNSForwardHTTP_handleSetConfig.json
@@ -30,6 +30,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -62,6 +63,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -95,6 +97,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -128,6 +131,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -161,6 +165,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -194,6 +199,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -227,6 +233,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -260,6 +267,7 @@
       "cache_size": 1024,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -293,6 +301,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -326,6 +335,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -361,6 +371,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -396,6 +407,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -430,6 +442,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -463,6 +476,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
@@ -498,6 +512,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": [
@@ -533,6 +548,7 @@
       "cache_size": 0,
       "cache_ttl_min": 0,
       "cache_ttl_max": 0,
+      "cache_optimistic": false,
       "resolve_clients": false,
       "use_private_ptr_resolvers": false,
       "local_ptr_upstreams": []
diff --git a/openapi/CHANGELOG.md b/openapi/CHANGELOG.md
index 3e2f0577..9a70bb9a 100644
--- a/openapi/CHANGELOG.md
+++ b/openapi/CHANGELOG.md
@@ -4,6 +4,14 @@
 
 ## v0.107: API changes
 
+### The new field `"cache_optimistic"` in DNS configuration
+
+* The new optional field `"cache_optimistic"` in `POST /control/dns_config`
+  method makes AdGuard Home use or not use the optimistic cache mechanism.
+
+* The new field `"cache_optimistic"` in `GET /control/dns_info` method is true
+  if AdGuard Home uses the optimistic cache mechanism.
+
 ### New possible value of `"interval"` field in `QueryLogConfig`
 
 * The value of `"interval"` field in `POST /control/querylog_config` and `GET
diff --git a/openapi/openapi.yaml b/openapi/openapi.yaml
index f2fdca6b..44c3c599 100644
--- a/openapi/openapi.yaml
+++ b/openapi/openapi.yaml
@@ -1322,6 +1322,8 @@
           'type': 'integer'
         'cache_ttl_max':
           'type': 'integer'
+        'cache_optimistic':
+          'type': 'boolean'
         'upstream_mode':
           'enum':
           - ''