This might include workstations, secure servers, and generally anything which is not public. For this example, we will be using the domain yourdomain.org as an example. We will create a subdomain priv.yourdomain.org which we will hide from everyone but our trusted friends. Here's the zone file for yourdomain.org as of 1999.07.08. 199907051 shows that this zone file was last updated on 1999 July 5 and is the first revision of that day.
Mail goes to mail.yourdomain.org.
Don't forget to change everything in bold to your own values. IN MX 5 mail.yourdomain.org . Here's the zone file for yourdomain.org as of 1999.07.08. If you can figure out the naming theme I used above, you get bonus points. Basically, you have to figure out what the above names nave in common.