RFC 1034+1035规定CNAME记录不应引起其他部分的处理。但我注意到像WordPress这样的服务越来越倾向于发送带有链式CNAME的附加部分。因此,如果不解析附加部分,就无法解码DNS响应。
例子:
例子:
;; QUESTION SECTION:
;after12.failblog.org. IN A
;; ANSWER SECTION:
after12.failblog.org. 3600 IN CNAME chzallnighter.wordpress.com.
vip-lb.wordpress.com. 300 IN A 72.233.104.123
vip-lb.wordpress.com. 300 IN A 76.74.255.117
vip-lb.wordpress.com. 300 IN A 74.200.247.187
vip-lb.wordpress.com. 300 IN A 74.200.247.59
vip-lb.wordpress.com. 300 IN A 76.74.255.123
vip-lb.wordpress.com. 300 IN A 72.233.127.217
;; AUTHORITY SECTION:
wordpress.com. 14400 IN NS ns1.wordpress.com.
wordpress.com. 14400 IN NS ns2.wordpress.com.
wordpress.com. 14400 IN NS ns3.wordpress.com.
wordpress.com. 14400 IN NS ns4.wordpress.com.
wordpress.com. 14400 IN NS ns5.wordpress.com.
wordpress.com. 14400 IN NS ns6.wordpress.com.
;; ADDITIONAL SECTION:
chzallnighter.wordpress.com. 300 IN CNAME vip-lb.wordpress.com.
ns1.wordpress.com. 14400 IN A 72.233.69.14
ns2.wordpress.com. 14400 IN A 76.74.159.137
ns3.wordpress.com. 14400 IN A 64.34.177.159
ns4.wordpress.com. 14400 IN A 72.233.104.98
ns5.wordpress.com. 14400 IN A 69.174.248.140
ns6.wordpress.com. 14400 IN A 64.34.174.135
请注意 chzallnighter.wordpress.com。300 IN CNAME vip-lb.wordpress.com. 在附加部分中,如果没有它,您将无法访问答案中的 A 记录。
为什么供应商要使用这种策略,它真正带来了什么好处?