about a query
Terry.
terry at list.dnsbed.com
Mon Feb 21 12:23:09 UTC 2011
Hello,
Please see the dig info below. ns1.dns-diy.com is the auth-server of
duowan.com domain.
My question is, when ns1.dns-diy.com answer with a CNAME for
"udb.duowan.com", and the answer also include an A RR for that alias,
how will the public DNS cache servers handle this answer?
Will the DNS cache use this A RR as result directly, or they make a
new request for the alias domain name udb.duowan.blogchina.org and
find the result?
Thanks!
$ dig udb.duowan.com +trace
; <<>> DiG 9.4.2-P2 <<>> udb.duowan.com +trace
;; global options: printcmd
. 108212 IN NS d.root-servers.net.
. 108212 IN NS e.root-servers.net.
. 108212 IN NS m.root-servers.net.
. 108212 IN NS b.root-servers.net.
. 108212 IN NS g.root-servers.net.
. 108212 IN NS l.root-servers.net.
. 108212 IN NS c.root-servers.net.
. 108212 IN NS i.root-servers.net.
. 108212 IN NS k.root-servers.net.
. 108212 IN NS a.root-servers.net.
. 108212 IN NS j.root-servers.net.
. 108212 IN NS h.root-servers.net.
. 108212 IN NS f.root-servers.net.
;; Received 512 bytes from 202.96.128.86#53(202.96.128.86) in 4 ms
com. 172800 IN NS h.gtld-servers.net.
com. 172800 IN NS g.gtld-servers.net.
com. 172800 IN NS e.gtld-servers.net.
com. 172800 IN NS c.gtld-servers.net.
com. 172800 IN NS d.gtld-servers.net.
com. 172800 IN NS a.gtld-servers.net.
com. 172800 IN NS l.gtld-servers.net.
com. 172800 IN NS f.gtld-servers.net.
com. 172800 IN NS k.gtld-servers.net.
com. 172800 IN NS b.gtld-servers.net.
com. 172800 IN NS i.gtld-servers.net.
com. 172800 IN NS m.gtld-servers.net.
com. 172800 IN NS j.gtld-servers.net.
;; Received 492 bytes from 128.8.10.90#53(d.root-servers.net) in 340 ms
duowan.com. 172800 IN NS ns1.dns-diy.com.
duowan.com. 172800 IN NS ns2.dns-diy.com.
;; Received 204 bytes from 192.35.51.30#53(f.gtld-servers.net) in 300 ms
udb.duowan.com. 90000 IN CNAME udb.duowan.blogchina.org.
udb.duowan.blogchina.org. 5 IN A 64.38.63.4
;; Received 86 bytes from 218.85.139.33#53(ns1.dns-diy.com) in 19 ms
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