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本帖最后由 silty 于 2010-05-31 17:29 编辑
1、我所查询到的“onlinenic.net”域的权威DNS为“ns1.dns-diy.com”:
C:\>dig ns onlinenic.net @a.gtld-servers.net
; <<>> DiG 9.6.1-P1 <<>> ns onlinenic.net @a.gtld-servers.net
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 270
;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 2, ADDITIONAL: 6
;; WARNING: recursion requested but not available
;; QUESTION SECTION:
;onlinenic.net. IN NS
;; AUTHORITY SECTION:
onlinenic.net. 172800 IN NS ns1.dns-diy.com.
onlinenic.net. 172800 IN NS ns2.dns-diy.com.
;; ADDITIONAL SECTION:
ns1.dns-diy.com. 172800 IN A 61.145.116.174
ns1.dns-diy.com. 172800 IN A 218.85.139.33
ns1.dns-diy.com. 172800 IN A 210.51.180.239
ns2.dns-diy.com. 172800 IN A 60.191.252.68
ns2.dns-diy.com. 172800 IN A 218.107.207.23
ns2.dns-diy.com. 172800 IN A 211.152.42.137
;; Query time: 343 msec
;; SERVER: 192.5.6.30#53(192.5.6.30)
;; WHEN: Mon May 31 16:44:54 2010
;; MSG SIZE rcvd: 174
C:\>dig ns1.onlinenic.net @127.0.0.1
; <<>> DiG 9.6.1-P1 <<>> ns1.onlinenic.net @127.0.0.1
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2017
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2
;; QUESTION SECTION:
;ns1.onlinenic.net. IN A
;; ANSWER SECTION:
ns1.onlinenic.net. 3243 IN A 64.84.29.56
;; AUTHORITY SECTION:
onlinenic.net. 170777 IN NS ns2.dns-diy.com.
onlinenic.net. 170777 IN NS ns1.dns-diy.com.
;; ADDITIONAL SECTION:
ns1.dns-diy.com. 244 IN A 218.85.139.33
ns2.dns-diy.com. 243 IN A 218.107.207.23
;; Query time: 15 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Mon May 31 17:25:05 2010
;; MSG SIZE rcvd: 130
C:\>dig ns1.onlinenic.net @ns1.dns-diy.com
; <<>> DiG 9.6.1-P1 <<>> ns1.onlinenic.net @ns1.dns-diy.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 108
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;ns1.onlinenic.net. IN A
;; ANSWER SECTION:
ns1.onlinenic.net. 3600 IN A 64.84.29.56
;; Query time: 31 msec
;; SERVER: 218.85.139.33#53(218.85.139.33)
;; WHEN: Mon May 31 17:28:35 2010
;; MSG SIZE rcvd: 51
C:\>dig ns1.onlinenic.net @ns1.onlinenic.net
; <<>> DiG 9.6.1-P1 <<>> ns1.onlinenic.net @ns1.onlinenic.net
;; global options: +cmd
;; connection timed out; no servers could be reached
结果并没有错误。至于楼主的结果,应该是onlinenic.com域更改了NS记录,即“ns1.onlinenic.net”A记录与a.gtld-servers.net上的NS记录不一致而已,并且ns1.onlinenic.net已不再是域“onlinenic.net”的权威NS
2、作为cache-DNS server来说,它会采用这个ADDITIONAL的IP来解析mail.onlinenic.com吗?
会,否则每个域名都从根服务器进行迭代查询,那开销未免也太大了
3、什么情况下采用,什么情况下不采用?
缓存服务器有该域的NS记录缓存结果时,直接采用,若没有,则是从根服务器开始迭代查询。
4、如何避免:这个,恩..重新编译bind,设定每个域名都从根开始迭代,或者不缓存解析结果。。。。。。
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