Max number of DNS domains for BIND

[Mogamat Kahaar]

Hi,

Have BIND 4.9.7 installed on our HPUX 10.20 Server. We are doing multiple DNS domain lookups (7 to be exact, inclusive of the local DNS domain). I was told that there is a limit. Does anyone know why/what the limit? Is there a way to overcome the limit?

tamia

Mo.

[Dirk Wiedemann]

Hello Mogamat,

afaik:
- there is no limit for domains (while enough memory and disk space)
- limit of distinct zones:
up to bind 8.1.1: max 32768 zones
bind 8.1.2: 65536 zones
bind 8.2 or higher: 16777216 zones

I think that should be enough.
Dirk

[Mogamat Kahaar]

Hi,

Thanks for the info. Maybe I did not explain myself too well :-) The issue is more with using the resolve.conf on an HPUX system where you need to resolve more than 6 DNS domains (we are using an HP product called VPO that is used too monitor systems in 6 different domains at the moment).

Is there a patch i can load or a file i can modify to allow me to resolve names for more than 6 domains?

domain1.com
domain2.com
....
domainx.com

[Christopher Caldwell]

You can query any number of domains regardless of resolv.conf. In 4.9.7 you can [apparently] only refer to as many as 3 name servers:

$man resolv.conf



nameserver Internet (IP) address, in dot notation, of a name
server that the resolver should query. Up to
MAXNS (currently 3) name servers can be listed,
one per keyword. If there are multiple servers,
the resolver library queries them in the order
listed. If no nameserver entries are present, the
default is to use the name server on the local
machine. (The algorithm used is: Try a name
server; if the query times out, try the next and
continue until all name servers have been tried,
then repeat trying all the name servers until a
maximum number of retries have been made).

[Mogamat Kahaar]

Hi Christopher,

A man on resolv.conf says:



search The search list is currently limited to six domains with a total of 256 characters.

The above is what concerns me since I have already reached the 6 domain search limit and now need to add an additional domain to the search list.

Regards

Mo.

[John Bolene]

Yes, 6 domains is the limit.

we now are at the limit also and will have to change eventually

we use

rc.us.hertz
dc.us.hertz
etc

and will have to change to just .hertz.com and have the rest as subdomains looked up on the root server

[Christopher Caldwell]

search domains are for unqualified names (search was designed to save typing), so if you've exceeded search domains (six is the limit), your choices are to fully qualify the names
e.g.
type a.b.c.com
instead of
a

or
to partially qualify the name and at the rest of the domain to the search directive.
resolv.conf
search c.com
on the command line:
telnet a.b

[Sean OB_1]

Why not set one of your DNS servers to forward requests for the other domains you need to look up?

In any case, why the need for 6 servers in resolv.conf?

Are these domains not registered in the root servers? If they are than any one server should be able to resolve the names. If they are not then I would suggest setting up a dns server to forward those domains to the appropriate server.

These is easy enough to do, simply add the zone in the named.conf file and tell it what server to forward the requests to.