Concise Guide to DNS and BIND, The

Wildcard Records

DNS has the concept of wildcard records. They are most often used for MX records. On first sight they seem useful enough, but they are counter intuitive and often used incorrectly.

In the penguin.bv zone mail could have been set up like this:

@               MX      10 mail
                MX      20 mail.herring.bv.
*               MX      10 mail
                MX      20 mail.herring.bv.
mail            MX      10 mail
                MX      20 mail.herring.bv.
rms             A       192.168.55.130

Which, by the way, is not the same as used to be in the penguin zone, and probably not what you, or I, want.

The proper name for the wildcard record is "*.penguin.bv". Thus it will not match a query for a MX record for "penguin.bv." A query for that will instead match the "@" record. A query for "mail.penguin.bv" will match the explicit record for mail, any ...