Canonical name record is an alias (or nickname) of one name to another.
The A record to which the alias points can be either local or remote - on a foreign name server. This is useful when running multiple services (like an FTP and a webserver) from a single IP address.
Each service can then have its own entry in DNS (like ftp.example.com. and www.example.com.). It is also used when running multiple HTTP servers, with different names, on the same physical host.
CNAME rules have the following format:
hostname. IN CNAME servername.
where:
hostname.
is the zone name or one of its subdomainsservername.
is a fully qualified domain name (FQDN) either inside or outside the zone.
Examples:
Code Block |
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ftp.domain.com. IN CNAME inside.domain.com.
ftp1.domain.com IN CNAME outside.zone.com.
k1._domainkey.domain.com IN CNAME dkim.zone.com. |
RFC 1034 states: “If a CNAME record is present at a node, no other data should be present; this ensures that the data for a canonical name and its aliases cannot be different.” In order for these requirements to be met in DNS Manager, the value specified in the Zone alias name field of the CNAME record cannot be set for the DNS Zone name filed in NS, A, AAAA, SRV, CNAME and TXT records or for the Zone email field in an MX record.
Click here for more info on this type of record.