Apple Workgroup Server 8550 - Manual (Page 46)

The ttl (time to live) subfield specifies the number of seconds for which the
record is valid. This subfield is optional. If it is not present, or if it is “-1”,
the record is always valid.
The class subfield is optional. The only value that is currently supported is
“IN” (Internet domain).
The type subfield is required and describes the type of identifier that
follows. Use “A” to indicate that an IP address follows. Use “CNAME” to
indicate that the identifier that follows is a canonical (“real”) name. Use
“NS” to indicate that the identifier that follows is a name server.
The identifier subfield is required and can be an IP address or a canonical
name.
Examples of valid hosts file records are:
apple.com A 130.43.2.2
; address of host apple.com
foobar CNAME barfoo.apple.com
; canonical name for the host whose local alias is “foobar”
xyzcorp.com 86400 NS biglist.xyzcorp.com
; name server for xyz corp (valid for one week)
The MacTCP application also allows you to use a hosts file. The format
requirements for the MacTCP hosts file are slightly different from the
format requirements for an Open Transport hosts file.
If you want to use a MacTCP hosts file from another computer, make sure
that all of the listed domain names are fully qualified. MacTCP allows the
hosts file to contain domain names that are not fully qualified. When used
with Open Transport, a domain name that is not fully qualified will cause
an error unless it is an alias.
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