Some techinical questions regarding bind Data

[Alex Ponnath]

Thanks,

I would never think anyone in its right mind would use 126 sublevels,
My question was just more to find out if there was a hard set limit
So I could consider it in my design. So as long as I stay under the 
255 total char for the combined length and no single segment is larger
Than 63 char

Thanks for the insight

Alex


-----Original Message-----
From: bind-users-bounce at isc.org [mailto:bind-users-bounce at isc.org] On
Behalf Of Peter Dambier
Sent: Sunday, February 24, 2008 10:02 AM
To: bind-users at isc.org
Subject: Re: Some techinical questions regarding bind Data


> On 24.02.08 08:32, Alex Ponnath wrote:

>> e) Is there a limit how many sub domain levels there can be like
>> "lax.ca.us.acme.com"

126

With a length of 255 and every second character a "." you can
get some 126 sublevels.

Well, it is supposed to get a test for single letters in the root.
At the moment you have at least two.

Let an answer for one level take some 50 msec, it might take longer.

126 levels will take 6.3 seconds. Long enough for your client
to timeout. If you have your own caching resolvers your query
might succeed the second try. If you are using a public resolver
like your ISP's then it will timeout the second time again.

People in canada and uk have been running away from names like
"someboy.co.qc.ca" to "somebody.tk" because it resolves faster.

dns has been designed as a tree with some k hosts in mind.
Today with the internaet running out of IPv4 addresses it has
deteriorated to a flat file with almost every host in ".com"

If you are running your own dns for your company and if you
can have your own domain cloned at every installation then
you can still have some 100 sublevels and have fast answers
but I guess that is a very special case :)

Kind regards
Peter and Karin

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