Check that www.nus.edu.sg 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 nus.edu.sg soa
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1316
;; flags: qr ra; QUERY: 1, ANSWER: 13, AUTHORITY: 0, ADDITIONAL: 14

;; QUESTION SECTION:
;.				IN	NS

;; ANSWER SECTION:
.			308297	IN	NS	g.root-servers.net.
.			308297	IN	NS	b.root-servers.net.
.			308297	IN	NS	k.root-servers.net.
.			308297	IN	NS	e.root-servers.net.
.			308297	IN	NS	i.root-servers.net.
.			308297	IN	NS	d.root-servers.net.
.			308297	IN	NS	f.root-servers.net.
.			308297	IN	NS	m.root-servers.net.
.			308297	IN	NS	c.root-servers.net.
.			308297	IN	NS	j.root-servers.net.
.			308297	IN	NS	h.root-servers.net.
.			308297	IN	NS	l.root-servers.net.
.			308297	IN	NS	a.root-servers.net.

;; ADDITIONAL SECTION:
a.root-servers.net.	177620	IN	A	198.41.0.4
a.root-servers.net.	177620	IN	AAAA	2001:503:ba3e::2:30
b.root-servers.net.	135884	IN	A	192.228.79.201
c.root-servers.net.	523668	IN	A	192.33.4.12
d.root-servers.net.	482017	IN	A	128.8.10.90
d.root-servers.net.	482017	IN	AAAA	2001:500:2d::d
e.root-servers.net.	133204	IN	A	192.203.230.10
f.root-servers.net.	178491	IN	A	192.5.5.241
f.root-servers.net.	483367	IN	AAAA	2001:500:2f::f
g.root-servers.net.	179155	IN	A	192.112.36.4
h.root-servers.net.	136193	IN	A	128.63.2.53
h.root-servers.net.	136193	IN	AAAA	2001:500:1::803f:235
i.root-servers.net.	177727	IN	A	192.36.148.17
i.root-servers.net.	177727	IN	AAAA	2001:7fe::53

;; Query time: 8 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Mon May 21 12:39:44 2012
;; MSG SIZE  rcvd: 512

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 498
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 4, ADDITIONAL: 8

;; QUESTION SECTION:
;nus.edu.sg.			IN	SOA

;; AUTHORITY SECTION:
sg.			172800	IN	NS	ns2.cuhk.edu.hk.
sg.			172800	IN	NS	sec3.apnic.net.
sg.			172800	IN	NS	dsany.sgnic.sg.
sg.			172800	IN	NS	sg-ns.anycast.pch.net.

;; ADDITIONAL SECTION:
ns2.cuhk.edu.hk.	172800	IN	A	137.189.6.21
sec3.apnic.net.		172800	IN	A	202.12.28.140
dsany.sgnic.sg.		172800	IN	A	194.0.1.16
sg-ns.anycast.pch.net.	172800	IN	A	204.61.216.57
ns2.cuhk.edu.hk.	172800	IN	AAAA	2405:3000:3:60::21
sec3.apnic.net.		172800	IN	AAAA	2001:dc0:1:0:4777::140
dsany.sgnic.sg.		172800	IN	AAAA	2001:678:4::10
sg-ns.anycast.pch.net.	172800	IN	AAAA	2001:500:14:6057:ad::1

;; Query time: 37 msec
;; SERVER: 2001:7fd::1#53(k.root-servers.net)
;; WHEN: Mon May 21 12:39:44 2012
;; MSG SIZE  rcvd: 319

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 468
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 3, ADDITIONAL: 1

;; QUESTION SECTION:
;nus.edu.sg.			IN	SOA

;; AUTHORITY SECTION:
edu.sg.			3600	IN	NS	DSANY.SGNIC.sg.
edu.sg.			3600	IN	NS	SG-NS.ANYCAST.PCH.NET.
edu.sg.			3600	IN	NS	NS2.CUHK.EDU.HK.

;; ADDITIONAL SECTION:
DSANY.SGNIC.sg.		3600	IN	A	194.0.1.16

;; Query time: 198 msec
;; SERVER: 2001:dc0:1:0:4777::140#53(sec3.apnic.net)
;; WHEN: Mon May 21 12:39:44 2012
;; MSG SIZE  rcvd: 134

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1461
;; flags: qr; QUERY: 1, ANSWER: 0, AUTHORITY: 5, ADDITIONAL: 2

;; QUESTION SECTION:
;nus.edu.sg.			IN	SOA

;; AUTHORITY SECTION:
nus.edu.sg.		3600	IN	NS	dnssec3.singnet.com.sg.
nus.edu.sg.		3600	IN	NS	ns2.nus.edu.sg.
nus.edu.sg.		3600	IN	NS	dnssec2.singnet.com.sg.
nus.edu.sg.		3600	IN	NS	dnssec1.singnet.com.sg.
nus.edu.sg.		3600	IN	NS	ns1.nus.edu.sg.

;; ADDITIONAL SECTION:
ns1.nus.edu.sg.		3600	IN	A	137.132.123.4
ns2.nus.edu.sg.		3600	IN	A	137.132.5.2

;; Query time: 110 msec
;; SERVER: 2405:3000:3:60::21#53(NS2.CUHK.EDU.HK)
;; WHEN: Mon May 21 12:39:44 2012
;; MSG SIZE  rcvd: 174

;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1255
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 5, ADDITIONAL: 5

;; QUESTION SECTION:
;nus.edu.sg.			IN	SOA

;; ANSWER SECTION:
nus.edu.sg.		7200	IN	SOA	ns1.nus.edu.sg. ccenet.nus.edu.sg. 2012051801 3600 1800 604800 7200

;; AUTHORITY SECTION:
nus.edu.sg.		7200	IN	NS	dnssec1.singnet.com.sg.
nus.edu.sg.		7200	IN	NS	ns2.nus.edu.sg.
nus.edu.sg.		7200	IN	NS	dnssec2.singnet.com.sg.
nus.edu.sg.		7200	IN	NS	ns1.nus.edu.sg.
nus.edu.sg.		7200	IN	NS	dnssec3.singnet.com.sg.

;; ADDITIONAL SECTION:
ns1.nus.edu.sg.		7200	IN	A	137.132.123.4
ns2.nus.edu.sg.		7200	IN	A	137.132.5.2
dnssec1.singnet.com.sg.	3600	IN	A	165.21.83.11
dnssec2.singnet.com.sg.	3600	IN	A	195.13.10.226
dnssec3.singnet.com.sg.	3600	IN	A	165.21.100.11

;; Query time: 283 msec
;; SERVER: 165.21.100.11#53(dnssec3.singnet.com.sg)
;; WHEN: Mon May 21 12:39:45 2012
;; MSG SIZE  rcvd: 265

HTTP

Looking for CNAME of www.nus.edu.sg
Checking if there is a AAAA for www.nus.edu.sg ... FAILED.


; <<>> DiG 9.4.1-P1 <<>> www.nus.edu.sg aaaa
;; global options:  printcmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 782
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0

;; QUESTION SECTION:
;www.nus.edu.sg.			IN	AAAA

;; AUTHORITY SECTION:
nus.edu.sg.		7200	IN	SOA	ns1.nus.edu.sg. ccenet.nus.edu.sg. 2012051801 3600 1800 604800 7200

;; Query time: 9 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Mon May 21 12:39:45 2012
;; MSG SIZE  rcvd: 79

Checking other options ... failed too.

SMTP

MX 20 mailb.nus.edu.sg
Looking for AAAA on mailb.nus.edu.sg
MX 20 mailc.nus.edu.sg
Looking for AAAA on mailc.nus.edu.sg
MX 20 maild.nus.edu.sg
Looking for AAAA on maild.nus.edu.sg
MX 20 maila.nus.edu.sg
Looking for AAAA on maila.nus.edu.sg

DNS

Looking for AAAA of NS ns1.nus.edu.sg
No AAAA record for ns1.nus.edu.sg
Looking for AAAA of NS dnssec3.singnet.com.sg
No AAAA record for dnssec3.singnet.com.sg
Looking for AAAA of NS ns2.nus.edu.sg
No AAAA record for ns2.nus.edu.sg
Looking for AAAA of NS dnssec1.singnet.com.sg
No AAAA record for dnssec1.singnet.com.sg
Looking for AAAA of NS dnssec2.singnet.com.sg
No AAAA record for dnssec2.singnet.com.sg

NTP

Looking for an A record for ntp.nus.edu.sg
Found an A or AAAA record. Now looking for a AAAA.
Cannot find a AAAA record for ntp.nus.edu.sg
Cannot find a AAAA record for ntp.ipv6.nus.edu.sg

XMPP

Looking for a SRV record for _xmpp-client._tcp.nus.edu.sg
Looking for a SRV record for _xmpp-server._tcp.nus.edu.sg

Last Updated: Mon May 21 03:09:48 2012 UTC