事实上DNS不仅仅是用来解释地址用的而且还可以回答更多关於网路和主机的其它信息其中很重要的一个功能就是可以供邮件系统进行路由。这些资料通常会以不同的“记录”名称出现在DNS的资料档案中。

　　下面让我们参考一个Linux的DNS档案看看这些记录是如何表示的

　　;
; Zone file for siyongc.domain
;
; Then full zone file
;
$TTL 86400
IN SOA redhat52.siyongc.domain. netman.siyongc.domain. (
1999092801 ; serial
8H ; refresh
2H ; retry
1W ; expire
1D ) ; minimun
;
IN TXT "A test domain, created by Netman"
IN NS redhat52
IN NS debian.home.
IN MX 10 redhat52.siyongc.domain.
IN MX 20 debian.home.
;
localhost IN A 127.0.0.1

　　gw IN A 192.168.0.17
IN HINFO "Redhat" "MASQ"
IN TXT "The masquerade gateway to internet"

　　redhat52 IN A 192.168.0.17
IN MX 10 redhat52
IN MX 20 debian.home.
IN HINFO "Dell PII 266" "Linux RedHat"
www IN CNAME redhat52
mail IN CNAME redhat52
ftp IN CNAME redhat52
news IN CNAME redhat52
smtp IN CNAME redhat52

　　pii266 IN A 192.168.0.15
IN MX 10 redhat52.siyongc.domain.
IN MX 20 debian.home.

　　slware36 IN A 192.168.0.18
IN MX 10 redhat52.siyongc.domain.
IN MX 20 debian.home.