为什么 Google 对 www 使用 A 记录而不是 CNAME？

Question

在这种情况下，A 是否比 CNAME 快得多？

$ dig www.google.com

; <<>> DiG 9.8.1-P1 <<>> www.google.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 28336
;; flags: qr rd ra; QUERY: 1, ANSWER: 6, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;www.google.com.                        IN      A

;; ANSWER SECTION:
www.google.com.         13      IN      A       173.194.78.103
www.google.com.         13      IN      A       173.194.78.106
www.google.com.         13      IN      A       173.194.78.105
www.google.com.         13      IN      A       173.194.78.99
www.google.com.         13      IN      A       173.194.78.147
www.google.com.         13      IN      A       173.194.78.104

;; Query time: 11 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Thu Jan 24 10:22:28 2013
;; MSG SIZE  rcvd: 128

Answer 1

好吧，如果你是谷歌，每天有数百万个 DNS 查询，我会说将查询减少 50% 是很重要的。