![在前向区域插入 mx 记录](https://linux22.com/image/664144/%E5%9C%A8%E5%89%8D%E5%90%91%E5%8C%BA%E5%9F%9F%E6%8F%92%E5%85%A5%20mx%20%E8%AE%B0%E5%BD%95.png)
使用 bind9 将 MX 记录添加到前向区域的正确方法是什么(以及为什么)?
选项 A
@ IN MX 10 mx1.example.com.
@ IN MX 20 mx2.example.com.
mx1.example.com. IN A a.b.c.d
mx2.example.com. IN A a.b.c.d
选项 B
example.com. IN MX 10 mx1.example.com.
example.com. IN MX 20 mx2.example.com.
mx1.example.com. IN A a.b.c.d
mx2.example.com. IN A a.b.c.d
或者还有其他选择吗?
答案1
$ORIGIN 定义一个基值,在处理区域文件时,将从该基值进行“非限定”名称(没有终止点的名称)替换。该@符号是区域文件中 $ORIGIN 的简写。
因此,使用简写@
或全名example.com.
是等效的。
$ORIGIN 可以在区域文件中明确指定,但通常从 Bind 配置文件中指定的区域名称中暗示:
// 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.
第三种选择是,区域文件中不以主机名、区域名称或区域来源的简写开头的行@成为上述记录的延续。
@ 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
也相当于:
@ 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.