DNS

Domain Name Service (DNS) is used to look up IP addresses from names (as well as other types of data).

DNS Relay

The FireBrick acts as a DNS relay. A DNS server is specified in the config, or as a the result of DHCP. Any requests to the FireBrick to UDP/TCP port 53 are simply mapped to the currently specified DNS server.

DNS Lookup

Most of the input fields for an IP address in the FireBrick can has a domain name specified instead. The FireBrick can look up a domain name where the result is a simple A record and replace with the IP address found. This requires a DNS server and routing (gateway and subnet or stealth) to be specified so that the FireBrick can send/receive the DNS request/reply. This is provide for convenience only, and will not work in all cases (e.g. CNAMEs).