Troubleshooting a DNS Zone

The first thing we need to do is set up named to use this new zone file. Edit /etc/named.conf, find the mylabserver.com zone declaration, and change the file line.

From:
zone "mylabserver.com" IN {
    type master;
    file "/var/named/forward.db";
};

To:
zone "mylabserver.com" IN {
    type master;
    file "/var/named/new-forward.db";
};

Second, we need to edit the new-forward.db zone file and make sure it's correct.

Open it with your favorite editor and take a look.

The first thing to notice is the domain that the file is set to SOA for. Since we're using mylaberver.com and the file contains oldcompany.edu, we need to change that in every location.

Additionally, the IP scheme for the zone file doesn't look right - our IP scheme is 10.0.1.XX while the one in the file is 10.10.1.XX. That should be fixed as well.

Verify the IP address of the 'A' record for dns.mylabserver.com is correct.

Verify that all FQDNs have a . at the end.

Once we have done all of that, we can verify that the file is correct by running:

named-checkzone mylabserver.com /var/named/new-forward.db

When we get a good result there, we can run:

systemctl restart named

Finally, we can check our work using nslookup in the next task.

Use the following commands to check what address a name resolves to:

nslookup dns.mylabserver.com localhost
nslookup test1.mylabserver.com localhost
nslookup db1.mylabserver.com localhost
nslookup web3.mylabserver.com localhost

• dns.mylabserver.com should resolve to your local IP address.
• test1.mylabserver.com should resolve to 10.0.1.30.
• db1.mylabserver.com should resolve to 10.0.1.78.
• web3.mylabserver.com should resolve to 10.0.1.230.