7. Finalize DNS configuration

The DNS configuration is missing because cobbler doesn’t know which subnets and domains it is responsible for. You have to inform the cobblerd daemon that it should create forward- and reverse-zone files for particular domains.

7.1. Forward zones

Remember that forward zones map a name such as c01.hpc to its IP 192.168.17.1. Cobbler already has the necessary information in its database since you added the system. Now all you need to do is tell it which zone files it should create.

Edit /etc/cobbler/settings and change the following value:

manage_forward_zones: ['mgmt', 'hpc']

This will add all .hpc and .mgmt IPs to their corresponding forward zone file. After editing settings remember to restart cobblerd. Then run cobbler sync.

The generated /etc/named.conf will now contain two zone definitions for mgmt and hpc.

zone "hpc." {
    type master;
    file "hpc";
};

zone "mgmt." {
    type master;
    file "mgmt";
};

These point to two newly created zone files /var/named/mgmt and /var/named/hpc.

$TTL 300
@                       IN      SOA     192.168.16.1. nobody.example.com. (
                                        2019021807   ; Serial
                                        600         ; Refresh
                                        1800         ; Retry
                                        604800       ; Expire
                                        300          ; TTL
                                        )

                        IN      NS      192.168.16.1.




c01  IN  A     192.168.1.1;

$TTL 300
@                       IN      SOA     192.168.16.1. nobody.example.com. (
                                        2019021807   ; Serial
                                        600         ; Refresh
                                        1800         ; Retry
                                        604800       ; Expire
                                        300          ; TTL
                                        )

                        IN      NS      192.168.16.1.




c01  IN  A     192.168.17.1;

These files are based on a default zone template found at /etc/cobbler/zone.template. You can create a custom template for each zone by copying and modifying the default template and placing them in /etc/cobbler/zone_templates. The filename has to match the final zone file name. E.g., for generating /var/named/mgmt create a template with the name /etc/cobbler/zone_templates/mgmt.

Do this now for both mgmt and hpc and try to make them similar to the files created in exercise 2. Keep template variables such as $cname_record and $host_record in place. This is where cobbler will insert content during sync.

7.2. Reverse zones

Recall that reverse zone definitions are used to lookup the name for a given IP. Cobbler can also generate those zone files. The mechanism is exactly the same as with forward zone file, the only difference now is that you will have to define zone template for every IP range.

Edit /etc/cobbler/settings and change the following value:

manage_reverse_zones: ['192.168.0', '192.168.1', '192.168.16', '192.168.17']

Similar to the forward zones, create templates such as /etc/cobbler/zone_templates/192.168.17 to ensure cobbler creates files that resemble to the ones you had during exercise 2.

7.2.1. Verify that DNS resolution and IPMI works

Make sure to verify DNS resolution and IPMI works before trying to proceed. Run cobbler sync to apply all configuration changes. Use the commands used in exercise 2 to verify DNS lookup in both directions.

7.2.2. Add the remaining systems to cobbler

Add the remaining compute nodes to cobbler by using cobbler system add and cobbler system edit. Finally run cobbler sync to update the configuration.

All of their interfaces should be configured, DNS forward and reverse lookup should work, and they should be reachable through IPMI.