PeerDNS
also: ignore-auto-dns
PeerDNS is a DNS configuration option in NetworkManager that allows the system to use DNS servers provided by VPN, DHCP, or other network connections, rather than only using manually configured servers.
PeerDNS controls whether NetworkManager accepts and uses DNS server information automatically discovered from network interfaces. When enabled (the default), it merges DNS settings from all active connections—such as DHCP leases, VPN configurations, or connection profiles—into the system resolver.
This is useful in dynamic environments where you connect to multiple networks with different DNS requirements. For example, when connecting to a corporate VPN, PeerDNS allows that VPN's DNS servers to be automatically used for name resolution without manual configuration.
You can disable PeerDNS per-connection in NetworkManager configuration files (typically in /etc/NetworkManager/system-connections/) by setting ignore-auto-dns=true, which forces the system to use only your explicitly configured DNS servers and ignore any provided by the network.