The first thing to do for this event is to perform the steps described in the event itself and assign a DNS sufix. If that doesn't fix it then you can look for other solutions.
This event may show up on computers that are not part of a domain (stand-alone). In this case it is not that important to have a DNS domain so you can ignore it. The only drawback is that if you want to access a computer on the local network you may have to provide the entire host name. For example, intranet.mycompany.com vs. intranet - if you had "mycompany.com" as the primary DNS domain then the computer would automatically append the ".mycompany.com" suffix to the "intranet" host name.
article provides more or less the same explanation as the event itself.
This event may olso occur if the PDC is no longer available (i.e. removed from the network without the proper transfer of its roles to other domain controllers). ME257623
may help in solving this problem.
From a newsgroup post: "The server is missing its primary DNS suffix. If the server is a member server or a stand alone server, right click on My Computer and choose properties. Click on the Network Identification tab and click properties. Then click the More button. In the Primary DNS suffix for this computer section, add the DNS suffix. If this machine is the member of an Active Directory, then the DNS suffix should be the AD domain name.
If this machine is a DC, open regedit. Go to HKLM\SYSTEM\CCS\Service\TCPIP\Parameters. In this key check for a value called "Domain". If it's there, it'll probably be blank. Open this value and add the AD domain name as the data. Next, check for the "NV Domain" key. Again, this value may be blank. Open it and add the AD domain name as the data. Reboot the server. If these keys do not exist, then create the keys as string values."