使用bind9将MXlogging添加到转发区域的正确方法（以及为什么）是什么？
选项A
@ IN MX 10 mx1.example.com. @ IN MX 20 mx2.example.com. mx1.example.com. IN A abcd mx2.example.com. IN A abcd 选项B
example.com. IN MX 10 mx1.example.com. example.com. IN MX 20 mx2.example.com. mx1.example.com. IN A abcd mx2.example.com. IN A abcd
还是有另一种select？
$ ORIGIN定义了一个基本值，在处理区域文件时，从其中取得“不合格”名称（那些没有终止点的）replace。 @符号是区域文件中的$ ORIGIN的简写。
使用简写@或全名example.com. 因此是等同的。
$ ORIGIN可以在区域文件中明确指定，但通常是在绑定configuration文件中指定的区域名称隐含的：
// named.conf file fragment zone "example.com" in{ type master; file "example.com.zone"; };
和
; example.com.zone file fragment ; no $ORIGIN present and is synthesized from the zone name in named.conf ==> example.com .... @ IN NS ns1.example.com. ; ns1.example.com. is the name server for example.com. @ IN MX 10 mx1.example.com. ; mx1.example.com. is the primary mailserver name for example.com. .... $ORIGIN uk.example.com. ; explicitly define or "reset" $ORIGIN to uk.example.com. ; doing this mid-way in a zone-file is not common practice anymore (if it ever was) ; but it will keep a large single zone-file somewhat more readable. @ IN NS ns2.example.com. ; functionally identical to ; uk.example.com. IN NS ns2.example.com ; ns2.example.com. is the name server for uk.example.com.
第三个选项是区域文件中以主机名，区域名称或区域原点的简写开始的行成为上述logging的延续。
@ IN MX 10 mx1.example.com. IN MX 20 mx2.example.com. ; another record for the @ record above IN NS ns1.example.com. ; yet another record for the @ record above IN NS ns2.example.com. ; and a 3rd continuation for the @ record above
也等同于：
@ IN MX 10 mx1.example.com. example.com. IN MX 20 mx2.example.com. IN NS ns1.example.com. ; NS record for the example.com. record above ; the continuation can be to set different ; record types for the same resource record name example.com. IN NS ns2.example.com. www IN A 10.9.8.7 IN A 192.168.0.1 ; or set multiple (round-robin) records when ; continuing with the same record type.