Check that www.hkbu.edu.hk 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 hkbu.edu.hk soa
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 284
;; flags: qr ra; QUERY: 1, ANSWER: 13, AUTHORITY: 0, ADDITIONAL: 14

;; QUESTION SECTION:
;.				IN	NS

;; ANSWER SECTION:
.			311820	IN	NS	k.root-servers.net.
.			311820	IN	NS	g.root-servers.net.
.			311820	IN	NS	i.root-servers.net.
.			311820	IN	NS	m.root-servers.net.
.			311820	IN	NS	h.root-servers.net.
.			311820	IN	NS	e.root-servers.net.
.			311820	IN	NS	j.root-servers.net.
.			311820	IN	NS	c.root-servers.net.
.			311820	IN	NS	b.root-servers.net.
.			311820	IN	NS	l.root-servers.net.
.			311820	IN	NS	f.root-servers.net.
.			311820	IN	NS	d.root-servers.net.
.			311820	IN	NS	a.root-servers.net.

;; ADDITIONAL SECTION:
a.root-servers.net.	181143	IN	A	198.41.0.4
a.root-servers.net.	181143	IN	AAAA	2001:503:ba3e::2:30
b.root-servers.net.	139407	IN	A	192.228.79.201
c.root-servers.net.	527191	IN	A	192.33.4.12
d.root-servers.net.	485540	IN	A	128.8.10.90
d.root-servers.net.	485540	IN	AAAA	2001:500:2d::d
e.root-servers.net.	136727	IN	A	192.203.230.10
f.root-servers.net.	182014	IN	A	192.5.5.241
f.root-servers.net.	486890	IN	AAAA	2001:500:2f::f
g.root-servers.net.	182678	IN	A	192.112.36.4
h.root-servers.net.	139716	IN	A	128.63.2.53
h.root-servers.net.	139716	IN	AAAA	2001:500:1::803f:235
i.root-servers.net.	181250	IN	A	192.36.148.17
i.root-servers.net.	181250	IN	AAAA	2001:7fe::53

;; Query time: 7 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Mon May 21 11:41:01 2012
;; MSG SIZE  rcvd: 512

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 765
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 8, ADDITIONAL: 13

;; QUESTION SECTION:
;hkbu.edu.hk.			IN	SOA

;; AUTHORITY SECTION:
hk.			172800	IN	NS	z.hkirc.net.hk.
hk.			172800	IN	NS	hk-ns.pch.net.
hk.			172800	IN	NS	sec3.apnic.net.
hk.			172800	IN	NS	ns2.hkirc.net.hk.
hk.			172800	IN	NS	adns1.berkeley.edu.
hk.			172800	IN	NS	ns2.cuhk.edu.hk.
hk.			172800	IN	NS	b.dns.tw.
hk.			172800	IN	NS	ns1.hkirc.net.hk.

;; ADDITIONAL SECTION:
b.dns.tw.		172800	IN	A	210.201.138.58
z.hkirc.net.hk.		172800	IN	A	194.146.106.70
ns1.hkirc.net.hk.	172800	IN	A	203.119.2.18
ns2.cuhk.edu.hk.	172800	IN	A	137.189.6.21
ns2.hkirc.net.hk.	172800	IN	A	203.119.87.19
sec3.apnic.net.		172800	IN	A	202.12.28.140
adns1.berkeley.edu.	172800	IN	A	128.32.136.3
hk-ns.pch.net.		172800	IN	A	204.61.216.46
b.dns.tw.		172800	IN	AAAA	2404:0:10a0::58
z.hkirc.net.hk.		172800	IN	AAAA	2001:67c:1010:17::53
ns2.cuhk.edu.hk.	172800	IN	AAAA	2405:3000:3:60::21
ns2.hkirc.net.hk.	172800	IN	AAAA	2001:dca:1000::cb77:5713
sec3.apnic.net.		172800	IN	AAAA	2001:dc0:1:0:4777::140

;; Query time: 129 msec
;; SERVER: 192.112.36.4#53(g.root-servers.net)
;; WHEN: Mon May 21 11:41:01 2012
;; MSG SIZE  rcvd: 488

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1570
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 2, ADDITIONAL: 2

;; QUESTION SECTION:
;hkbu.edu.hk.			IN	SOA

;; AUTHORITY SECTION:
hkbu.edu.hk.		28800	IN	NS	DNS01.hkbu.edu.hk.
hkbu.edu.hk.		28800	IN	NS	DNS3.hkbu.edu.hk.

;; ADDITIONAL SECTION:
DNS3.hkbu.edu.hk.	28800	IN	A	175.159.154.59
DNS01.hkbu.edu.hk.	28800	IN	A	175.159.154.9

;; Query time: 113 msec
;; SERVER: 203.119.2.18#53(ns1.hkirc.net.hk)
;; WHEN: Mon May 21 11:41:01 2012
;; MSG SIZE  rcvd: 100

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 670
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 2, ADDITIONAL: 2

;; QUESTION SECTION:
;hkbu.edu.hk.			IN	SOA

;; ANSWER SECTION:
hkbu.edu.hk.		86400	IN	SOA	dns01.hkbu.edu.hk. root.dns01.hkbu.edu.hk. 36 10800 900 604800 86400

;; AUTHORITY SECTION:
hkbu.edu.hk.		86400	IN	NS	dns3.hkbu.edu.hk.
hkbu.edu.hk.		86400	IN	NS	dns01.hkbu.edu.hk.

;; ADDITIONAL SECTION:
dns3.hkbu.edu.hk.	86400	IN	A	175.159.154.59
dns01.hkbu.edu.hk.	86400	IN	A	175.159.154.9

;; Query time: 112 msec
;; SERVER: 175.159.154.9#53(DNS01.hkbu.edu.hk)
;; WHEN: Mon May 21 11:41:01 2012
;; MSG SIZE  rcvd: 141

HTTP

Looking for CNAME of www.hkbu.edu.hk
Checking if there is a AAAA for www.hkbu.edu.hk ... FAILED.


; <<>> DiG 9.4.1-P1 <<>> www.hkbu.edu.hk aaaa
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 997
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;www.hkbu.edu.hk.		IN	AAAA

;; AUTHORITY SECTION:
hkbu.edu.hk.		10800	IN	SOA	dns3.hkbu.edu.hk. root.dns3.hkbu.edu.hk. 38 10800 900 604800 86400

;; Query time: 4 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Mon May 21 11:41:02 2012
;; MSG SIZE  rcvd: 79

Checking other options ... failed too.

SMTP

MX 0 mailgwy3.hkbu.edu.hk
Looking for AAAA on mailgwy3.hkbu.edu.hk

DNS

Looking for AAAA of NS dns01.hkbu.edu.hk
No AAAA record for dns01.hkbu.edu.hk
Looking for AAAA of NS dns3.hkbu.edu.hk
No AAAA record for dns3.hkbu.edu.hk

NTP

Looking for an A record for ntp.hkbu.edu.hk
Looking for an A record for clock.hkbu.edu.hk
Looking for an A record for time.hkbu.edu.hk
Looking for an A record for chime.hkbu.edu.hk

XMPP

Looking for a SRV record for _xmpp-client._tcp.hkbu.edu.hk
Looking for a SRV record for _xmpp-server._tcp.hkbu.edu.hk

Last Updated: Mon May 21 02:11:04 2012 UTC