resolver

Configures name servers used to resolve names of upstream servers into addresses, for example:

resolver 127.0.0.1 [::1]:5353;

An address can be specified as a domain name or IP address, and an optional port (1.3.1, 1.2.2). If port is not specified, the port 53 is used. Name servers are queried in a round-robin fashion.

Before version 1.1.7, only a single name server could be configured. Specifying name servers using IPv6 addresses is supported starting from versions 1.3.1 and 1.2.2.

By default, nginx will look up both IPv4 and IPv6 addresses while resolving. If looking up of IPv6 addresses is not desired, the ipv6=off parameter can be specified.

Resolving of names into IPv6 addresses is supported starting from version 1.5.8.

By default, nginx caches answers using the TTL value of a response. An optional valid parameter allows overriding it:

resolver 127.0.0.1 [::1]:5353 valid=30s;

Before version 1.1.9, tuning of caching time was not possible, and nginx always cached answers for the duration of 5 minutes.

To prevent DNS spoofing, it is recommended configuring DNS servers in a properly secured trusted local network.