2.11 Adding a
You want to add a multihomed host to DNS.
Add multiple A records to the host's domain
, one per IP address. For example, for a file server with two network interfaces, you might add these records:
fs.foo.example. IN A 10.0.0.9
fs.foo.example. IN A 192.168.0.9
To handle reverse mapping for the host, add one PTR record to each of the appropriate two reverse-mapping zones:
18.104.22.168.in-addr.arpa. IN PTR fs.foo.example.
22.214.171.124.in-addr.arpa. IN PTR fs.foo.example.
looking up the address of
will see both IP addresses, and can choose which one to use (though most clients will just use the first address returned). Remember that, by default, they'll be returned in round
For troubleshooting purposes, you may want to add two more A records, each of which maps to just one of your multihomed host's addresses. For example:
fs-eth0.foo.example. IN A 10.0.0.9
fs-eth1.foo.example. IN A 192.168.0.9
This lets you test whether a particular network interface on the file server is up, by pinging
, for instance. You probably shouldn't add PTR records mapping the addresses back to these interface-specific
, though: most software can't handle multiple reverse mappings for a single IP address.
2.11.4 See Also
Section 2.8 for the behavior of round robin, and Chapter 4 of
DNS and BIND