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Low-level Settings guide


This article covers AdGuard for iOS, a multifunctional ad blocker that protects your device at the system level. To see how it works, download the AdGuard app

How to reach the Low-level settings


Changing Low-level settings can cause problems with the performance of AdGuard, may break the Internet connection or compromise your security and privacy. This section should only be opened if you know what you are doing, or you were asked to do so by our support team.

To go to Low-level settings, tap the gear icon at the bottom right of the screen to open Settings. Select the General section and then toggle on the Advanced mode switch, after that the Advanced settings section will appear below. Tap Advanced settings to reach the Low-level settings section.

Low-level settings

Tunnel mode

There are two main tunnel modes: Split and Full. Split-Tunnel mode provides compatibility of AdGuard and so-called "Personal VPN" apps. In Full-Tunnel mode no other VPN can work simultaneously with AdGuard.

There is a specific feature of Split-Tunnel mode: if DNS proxy does not perform well, for example, if the response from the AdGuard DNS server was not returned in time, iOS will "amerce" it and reroute traffic through DNS server, specified in iOS settings. No ads are blocked at this time and DNS traffic is not encrypted.

In Full-Tunnel mode only the DNS server specified in AdGuard settings is used. If it does not respond, the Internet will simply not work. Enabled Full-Tunnel mode may cause the incorrect performance of some programs (for instance, Facetime), and lead to problems with app updates.

By default, AdGuard uses Split-Tunnel mode as the most stable option.

There is also an additional mode called Full-Tunnel (without VPN icon). This is exactly the same as Full-Tunnel mode, but it is set up so that the VPN icon is not displayed in the system line.

Blocking mode

In this module you can select the way AdGuard will respond to DNS queries that should be blocked:

  • Default — respond with zero IP address when blocked by adblock-style rules; respond with the IP address specified in the rule when blocked by /etc/hosts-style rules
  • REFUSED — respond with REFUSED code
  • NXDOMAIN — respond with NXDOMAIN code
  • Unspecified IP — respond with zero IP address
  • Custom IP — respond with a manually set IP address

Block IPv6

By moving the toggle to the right, you activate the blocking of IPv6 queries (AAAA requests). AAAA-type DNS requests will not be resolved, hence only IPv4 queries can be processed.

Blocked response TTL

Here you can set the period for a device to cache the response to a DNS request. During the specified time to live (in seconds) the request can be read from the cache without re-requesting the DNS server.

Bootstrap servers

For DNS-over-HTTPS, DNS-over-TLS, and DNS-over-QUIC a bootstrap server is required for getting the IP address of the main DNS server. If not specified, the DNS server from iOS settings is used as the bootstrap server.

Fallback servers

Here you can specify an alternate server to which a request will be rerouted if the main server fails to respond. If not specified, the system DNS server will be used as the fallback. It is also possible to specify none, in this case, there will be no fallback server set and only the main DNS server will be used.

Background app refresh time

Here you can select the frequency at which the application will check for filter updates while in the background. Note that update checks will not be performed more often than the specified period, but the exact intervals may not be respected.