Concise Guide to DNS and BIND, The

The Trouble with CNAME Records

In Chapter 2 I presented the zone penguin.bv, of which this is a fragment:

@       3600    SOA     ns.penguin.bv.  hostmaster.penguin.bv. (
                2000041300      ; serial
                86400           ; refresh, 24h
                7200            ; retry, 2h
                3600000         ; expire, 1000h
                172800          ; minimum, 2 days
                )
                NS      ns
                NS      ns.herring.bv.
                MX      10 mail
                MX      20 mail.herring.bv.

; Nameserver
ns              A       192.168.55.2

; Mailserver, same machine.
mail            A       192.168.55.2
                MX      10 mail
                MX      20 mail.herring.bv.
                HINFO   PC Tunes

When one host has several names, for whatever reason, CNAME records are often used. Modern BINDs restricts the use of CNAME records quite severely. The restrictions were in the RFCs from the beginning, but it was never enforced. BIND 8 enforces them. The main rule is that a name that has a CNAME ...