AD, multiple DCs and DNS

We have a single domain, using the root of our FQDN (example.com) and the A record for the domain points to the IP of our first domain controller:

example.com    86400    IN    A    10.11.12.13

What I am wondering is whether we also should have the IPs for our other DCs, which are located at our other sites:

example.com    86400    IN    A    10.11.12.13
                         86400    IN    A    10.11.13.13
                         86400    IN    A    10.11.14.13

or if the configuration we have there is correct as it stands? I am betting you want all of the DCs there so that if 10.11.12.13 is unavailable AD still works.