nslookup returns can't resolve '(null)'

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arrmo
DD-WRT Novice


Joined: 05 Apr 2010
Posts: 32
PostPosted: Thu Jul 27, 2017 3:01    Post subject: nslookup returns can't resolve '(null)' Reply with quote
Hi,

There seem to be some postings about this, but it seems unless I force nslookup to query a particular name server, the first output from nslookup (dnsmasq?) is always,

can't resolve '(null)'

Anyone know of a fix for this?

Thanks!
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James2k
DD-WRT Guru


Joined: 23 Oct 2011
Posts: 549
PostPosted: Thu Jul 27, 2017 19:02    Post subject: Reply with quote
Syntax of nslookup on DD-WRT is:

Code:
nslookup [DOMAIN] [SERVER]


So to query a specific domain use Google public DNS:

Code:
nslookup dd-wrt.com 8.8.8.8


This would return something like this:

Quote:
Server: 8.8.8.8
Address 1: 8.8.8.8 google-public-dns-a.google.com

Name: dd-wrt.com
Address 1: 83.141.4.210 mail.dd-wrt.com

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arrmo
DD-WRT Novice


Joined: 05 Apr 2010
Posts: 32
PostPosted: Thu Jul 27, 2017 19:16    Post subject: Reply with quote
Yes, and that works! But if I don't specify the server, it should default to the DNS servers past to the WAN interface via DHCP ... which it does, after it first tries some other server (that shouldn't be checked).

Make sense?

Thanks!
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yoyoma2
DD-WRT User


Joined: 24 Sep 2016
Posts: 372
PostPosted: Sat Nov 18, 2017 3:11    Post subject: Reply with quote
James2k wrote:
Syntax of nslookup on DD-WRT is:

Code:
nslookup [DOMAIN] [SERVER]


But nslookup itself says that the server is optional.
Code:
# nslookup
BusyBox v1.27.2 (2017-11-03 23:24:05 CET) multi-call binary.

Usage: nslookup [HOST] [SERVER]

Query the nameserver for the IP address of the given HOST
optionally using a specified DNS server
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arrmo
DD-WRT Novice


Joined: 05 Apr 2010
Posts: 32
PostPosted: Sat Nov 18, 2017 18:32    Post subject: Reply with quote
Yes, agreed! It is optional, but if not specified defaults to what the WAN (DHCP) provides. And this is blank currently - that's the issue.

Thanks!
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