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DNS

The DNS resolver is responsible for resolving human-readable domain names into IP addresses and other type of machine-readable records. This is done by sending DNS queries to a DNS server, which then responds with the associated record of the domain name in question.

Settings

The DNS resolver is configured with the following attributes, which are available under the resolver key:

  • type: The type of the DNS resolver.
  • preserve-intermediates: Whether to preserve the intermediate name servers in the DNS resolution results.
  • concurrency: The number of concurrent resolution requests that can be made at the same time.
  • timeout: The time after which a resolution request will be timed out if no response is received.
  • attempts: The number of times a resolution request will be retried before it is considered failed.
  • try-tcp-on-error: Whether to try using TCP for resolution requests if an error occurs during a UDP resolution request.

The supported DNS resolver types for the resolver.type value are:

  • system: Use the system's default DNS resolver.
  • cloudflare: Use Cloudflare's public DNS service.
  • cloudflare-tls: Use Cloudflare's public DNS service over a secure TLS connection.
  • quad9: Use Quad9's public DNS service.
  • quad9-tls: Use Quad9's public DNS service over a secure TLS connection.
  • google: Use Google's public DNS service.
  • custom: Use a custom list of DNS servers which are specified under the resolver.custom key.

When using a custom DNS resolver, the list of DNS servers have to be specified under the resolver.custom key using the [protocol://]IP:PORT format. For example:

[resolver]
custom = ["udp://192.0.2.1:55", "tcp://192.0.2.3:55", "8.8.8.8"]

Please note that system or custom should be used when using DNS block lists as lookups from public DNS services are not allowed by most DNSBL services.

Example

[resolver]
type = "system"
preserve-intermediates = true
concurrency = 2
timeout = "5s"
attempts = 2
try-tcp-on-error = true