Check that www.imu.edu.cn exists for IPv4 in case we have a typo on the domain name. Use dig to query the local name server (::1).


; <<>> DiG 9.4.1-P1 <<>> +trace +all imu.edu.cn soa
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1804
;; flags: qr ra; QUERY: 1, ANSWER: 13, AUTHORITY: 0, ADDITIONAL: 14

;; QUESTION SECTION:
;.				IN	NS

;; ANSWER SECTION:
.			310759	IN	NS	f.root-servers.net.
.			310759	IN	NS	l.root-servers.net.
.			310759	IN	NS	c.root-servers.net.
.			310759	IN	NS	k.root-servers.net.
.			310759	IN	NS	m.root-servers.net.
.			310759	IN	NS	g.root-servers.net.
.			310759	IN	NS	d.root-servers.net.
.			310759	IN	NS	j.root-servers.net.
.			310759	IN	NS	i.root-servers.net.
.			310759	IN	NS	h.root-servers.net.
.			310759	IN	NS	e.root-servers.net.
.			310759	IN	NS	b.root-servers.net.
.			310759	IN	NS	a.root-servers.net.

;; ADDITIONAL SECTION:
a.root-servers.net.	180082	IN	A	198.41.0.4
a.root-servers.net.	180082	IN	AAAA	2001:503:ba3e::2:30
b.root-servers.net.	138346	IN	A	192.228.79.201
c.root-servers.net.	526130	IN	A	192.33.4.12
d.root-servers.net.	484479	IN	A	128.8.10.90
d.root-servers.net.	484479	IN	AAAA	2001:500:2d::d
e.root-servers.net.	135666	IN	A	192.203.230.10
f.root-servers.net.	180953	IN	A	192.5.5.241
f.root-servers.net.	485829	IN	AAAA	2001:500:2f::f
g.root-servers.net.	181617	IN	A	192.112.36.4
h.root-servers.net.	138655	IN	A	128.63.2.53
h.root-servers.net.	138655	IN	AAAA	2001:500:1::803f:235
i.root-servers.net.	180189	IN	A	192.36.148.17
i.root-servers.net.	180189	IN	AAAA	2001:7fe::53

;; Query time: 7 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Mon May 21 11:58:42 2012
;; MSG SIZE  rcvd: 512

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 90
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 6, ADDITIONAL: 8

;; QUESTION SECTION:
;imu.edu.cn.			IN	SOA

;; AUTHORITY SECTION:
cn.			172800	IN	NS	a.dns.cn.
cn.			172800	IN	NS	d.dns.cn.
cn.			172800	IN	NS	b.dns.cn.
cn.			172800	IN	NS	e.dns.cn.
cn.			172800	IN	NS	ns.cernet.net.
cn.			172800	IN	NS	c.dns.cn.

;; ADDITIONAL SECTION:
a.dns.cn.		172800	IN	A	203.119.25.1
b.dns.cn.		172800	IN	A	203.119.26.1
c.dns.cn.		172800	IN	A	203.119.27.1
d.dns.cn.		172800	IN	A	203.119.28.1
e.dns.cn.		172800	IN	A	203.119.29.1
ns.cernet.net.		172800	IN	A	202.112.0.44
a.dns.cn.		172800	IN	AAAA	2001:dc7::1
d.dns.cn.		172800	IN	AAAA	2001:dc7:1000::1

;; Query time: 180 msec
;; SERVER: 192.228.79.201#53(b.root-servers.net)
;; WHEN: Mon May 21 11:58:42 2012
;; MSG SIZE  rcvd: 291

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1862
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 5, ADDITIONAL: 2

;; QUESTION SECTION:
;imu.edu.cn.			IN	SOA

;; AUTHORITY SECTION:
edu.cn.			172800	IN	NS	dns2.edu.cn.
edu.cn.			172800	IN	NS	deneb.dfn.de.
edu.cn.			172800	IN	NS	dns.edu.cn.
edu.cn.			172800	IN	NS	ns2.cuhk.hk.
edu.cn.			172800	IN	NS	ns2.cernet.net.

;; ADDITIONAL SECTION:
dns.edu.cn.		172800	IN	A	202.112.0.35
dns2.edu.cn.		172800	IN	A	202.112.0.13

;; Query time: 111 msec
;; SERVER: 203.119.26.1#53(b.dns.cn)
;; WHEN: Mon May 21 11:58:42 2012
;; MSG SIZE  rcvd: 176

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2003
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 2, ADDITIONAL: 2

;; QUESTION SECTION:
;imu.edu.cn.			IN	SOA

;; AUTHORITY SECTION:
imu.edu.cn.		172800	IN	NS	GUS.BUPTNET.edu.cn.
imu.edu.cn.		172800	IN	NS	NMG1.imu.edu.cn.

;; ADDITIONAL SECTION:
GUS.BUPTNET.edu.cn.	172800	IN	A	202.112.10.36
NMG1.imu.edu.cn.	172800	IN	A	202.207.0.6

;; Query time: 111 msec
;; SERVER: 137.189.6.21#53(ns2.cuhk.hk)
;; WHEN: Mon May 21 11:58:42 2012
;; MSG SIZE  rcvd: 105

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: REFUSED, id: 479
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0

;; QUESTION SECTION:
;imu.edu.cn.			IN	SOA

;; Query time: 149 msec
;; SERVER: 202.112.10.36#53(GUS.BUPTNET.edu.cn)
;; WHEN: Mon May 21 11:58:44 2012
;; MSG SIZE  rcvd: 28

HTTP

Looking for CNAME of www.imu.edu.cn
Checking if there is a AAAA for www.imu.edu.cn ... FAILED.


; <<>> DiG 9.4.1-P1 <<>> www.imu.edu.cn aaaa
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 936
;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;www.imu.edu.cn.			IN	AAAA

;; ANSWER SECTION:
www.imu.edu.cn.		86399	IN	CNAME	fox.imu.edu.cn.

;; AUTHORITY SECTION:
imu.edu.cn.		10800	IN	SOA	nmg1.imu.edu.cn. mailmaster.nmg1.imu.edu.cn. 2006080901 10800 3600 604800 86400

;; Query time: 4 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Mon May 21 11:58:45 2012
;; MSG SIZE  rcvd: 102

Checking other options ... succeeded as www.imu6.edu.cn.
Sending...

HEAD / HTTP/1.1
Host: www.imu6.edu.cn
User-Agent: ipv6-survey.pl/1.97 http://www.mrp.net/IPv6_Survey.html

Reading ...

HTTP/1.1 200 OK
Date: Mon, 21 May 2012 01:26:27 GMT
Server: Apache/2.0.52 (Red Hat)
Last-Modified: Fri, 23 Mar 2012 02:06:59 GMT
ETag: "db7c2-8f06-7ac9f6c0"
Accept-Ranges: bytes
Content-Length: 36614
Connection: close
Content-Type: text/html; charset=GB2312

Accessed / [2001:da8:21d:0:0:0:0:88] Response: HTTP/1.1 200 OK

SMTP

MX 5 imugw.imu.edu.cn
Looking for AAAA on imugw.imu.edu.cn

DNS

Looking for AAAA of NS nmg1.imu.edu.cn
No AAAA record for nmg1.imu.edu.cn

NTP

Looking for an A record for ntp.imu.edu.cn
Looking for an A record for clock.imu.edu.cn
Looking for an A record for time.imu.edu.cn
Looking for an A record for chime.imu.edu.cn

XMPP

Looking for a SRV record for _xmpp-client._tcp.imu.edu.cn
Looking for a SRV record for _xmpp-server._tcp.imu.edu.cn

Last Updated: Mon May 21 02:30:10 2012 UTC