Troubleshooting DNS issues using nsloookup

Troubleshooting DNS issues using nsloookup

Postby stephen » Wed Mar 11, 2009 6:42 am

Troubleshooting DNS issues
This article from Microsoft Technet has tips on using the nslookup command to troubleshoot dns issues

Incorrect Subdomain Delegation
http://technet.microsoft.com/en-us/library/bb726934.aspx
C:\> nslookup
Default Server: terminator.movie.edu
Address: 192.249.249.3
> server a.gtld-servers.net. --Set server to the parent name
--server you suspect has bad delegation
Default Server: a.gtld-servers.net
Address: 198.41.0.4

> set type=ns --Look for NS records
> hp.com. --for the zone in question
Server: a.gtld-servers.net
Address: 198.41.0.4

Non-authoritative answer:
hp.com nameserver = RELAY.HP.COM
hp.com nameserver = HPLABS.HPL.HP.COM
hp.com nameserver = NNSC.NSF.NET
hp.com nameserver = HPSDLO.SDD.HP.COM

Authoritative answers can be found from:
hp.com nameserver = RELAY.HP.COM
hp.com nameserver = HPLABS.HPL.HP.COM
hp.com nameserver = NNSC.NSF.NET
hp.com nameserver = HPSDLO.SDD.HP.COM
RELAY.HP.COM internet address = 15.255.152.2
HPLABS.HPL.HP.COM internet address = 15.255.176.47
NNSC.NSF.NET internet address = 128.89.1.178
HPSDLO.SDD.HP.COM internet address = 15.255.160.64
HPSDLO.SDD.HP.COM internet address = 15.26.112.11

Let's say you suspect that the delegation to hpsdlo.sdd.hp.com is incorrect. Query hpsdlo for data in the hp.com zone, and check the answer:

> server hpsdlo.sdd.hp.com.
Default Server: hpsdlo.sdd.hp.com
Addresses: 15.255.160.64, 15.26.112.11

> set norecurse
> set type=soa
> hp.com.
Server: hpsdlo.sdd.hp.com
Addresses: 15.255.160.64, 15.26.112.11

Non-authoritative answer:
hp.com
origin = relay.hp.com
mail addr = hostmaster.hp.com
serial = 1001462
refresh = 21600 (6 hours)
retry = 3600 (1 hour)
expire = 604800 (7 days)
minimum ttl = 86400 (1 day)

Authoritative answers can be found from:
hp.com nameserver = RELAY.HP.COM
hp.com nameserver = HPLABS.HPL.HP.COM
hp.com nameserver = NNSC.NSF.NET
RELAY.HP.COM internet address = 15.255.152.2
HPLABS.HPL.HP.COM internet address = 15.255.176.47
NNSC.NSF.NET internet address = 128.89.1.178

If hpsdlo really were authoritative, it would have responded with an authoritative answer. The administrator of the hp.com zone can tell you whether hpsdlo should be an authoritative name server for hp.com, so that's who you should contact.
stephen
 
Posts: 507
Joined: Thu Feb 09, 2006 9:37 am
Location: Brisbane

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