Change in behaviour regarding ndots and searchlist

Lightner, Jeff JLightner at
Mon Sep 15 12:29:22 UTC 2014

I've begun seeing this recently in nslookup on Windows workstations as well.    It appears it is appending search domains even when I've specified an FQDN.   That is I have two search domains such as and and I typed short name "ralph" for nslookup or host it would give me "" IP if it existed or "" if the didn't exist and the latter did.   Now what I'm seeing is even if I specify "" it is looking up and failing on "".

If I put a dot at the end of the FQDN (e.g. instead of just it doesn't do that.    The Windows admins recently built a couple of new domain controllers for Windows DNS so I assumed it had something to do with those.   Do you by any chance have Windows DNS in your environment?

There was an article posted last week to this forum regarding bleed over of internal domains to the internet and vice-versa when one is using a domain internally that might be registered to someone else externally which is the case in our environment.    It may also be that the issue is because the formerly externally registered domain appears to have gone to expired/renewal status recently and it may be the Registrar is somehow causing this bleed over effect in the way they present records.

-----Original Message-----
From: bind-users-bounces at [mailto:bind-users-bounces at] On Behalf Of Mark Andrews
Sent: Monday, September 15, 2014 5:16 AM
To: BIND Users
Subject: Re: Change in behaviour regarding ndots and searchlist

Partially qualified names are DANGEROUS.  You realy do not want to use them ever no matter how convient or useful they appear to be.

In message <20140915083532.GA29404 at>, Sebastian Wiesinger w
> Hello,
> I noticed a change in the host tool in regard to how searches are done
> when there are >= "ndots" dots in the query. In the following case
> ndots is always nonexistant in the configuration.
> With bind 9.8 (Debian 1:9.8.4.dfsg.P1):
> $ host -d test.example
> Trying "test.example"
> Received 105 bytes from in 6 ms Trying
> ""
> Trying ""
> Trying ""
> Trying ""
> Trying ""
> Trying ""
> Host test.example not found: 3(NXDOMAIN) Received 104 bytes from
> in 1 ms
> With bind 9.9 (Debian 1:9.9.5.dfsg-4~bpo70, same on Ubuntu
> 1:9.9.5.dfsg-3):
> $ host -d test.example
> Trying "test.example"
> Host test.example not found: 3(NXDOMAIN) Received 105 bytes from
> in 15 ms Received 105 bytes from in 15 ms
> So with "host" from bind 9.8 the absolute name is tried first and
> after that the search list is tried.
> With bind 9.9 this is no longer the case.
> Does anyone know if that was a deliberate change? I liked the old
> behaviour because I could search for internal subdomains without
> specifying/knowing the full FQDN.
> As a workaround I raised the ndots value to 2 but that increases the
> number of queries because the searchlist is tried first for things
> like Also it increases the potential for MITM as
> "" is tried first.
> Regards
> Sebastian
> --
> GPG Key: 0x93A0B9CE (F4F6 B1A3 866B 26E9 450A  9D82 58A2 D94A 93A0
>             -- Terry Pratchett, The Fifth Elephant
> _______________________________________________
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Mark Andrews, ISC
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