RE: netmon and /etc/hosts ?

2000-06-15 12:10:02
Subject: RE: netmon and /etc/hosts ?
From: REIBENSCHUH Alfred <alfred.reibenschuh AT it-austria DOT com>
To: nv-l AT lists.tivoli DOT com
Date: Thu, 15 Jun 2000 18:10:02 +0200
>  1. Originally you said that you were blocked in some system calls that
>     1 to 2 mins.  I assume you were talking about the gethostbyaddr()
>  2. You have an 4 way  s7a with 8GB RAM.
>  3. You have an /etc/resolv.conf file

>Your problem cannot be with the /etc/hosts file.  There is no way an s7a
>sufficeint memory to suck up a large /etc/hosts file is going to take 1 to
>minutes to parse it.    

during a debugging session the gethostbyname() calls take for about 1 minute
NOT the gethostbyaddr() calls 

>You must have a problem with DNS.  Further, it
>appears that the addresses you are trying to resolve are not in /etc/hosts
>(since your netsvc.conf file says to use local /etc/hosts first, then DNS).
>Also, I don't think you can run bind on the loopback address only.  Maybe
>are running named, and /etc/resolv.conf has the nameserver set to

ok, once more

we have a combined host/dns resolving strategy 
with resolv order hosts-file then dns

we have a named(bind) running on the netview-host
in caching-only mode (do you know what means?)

the named is configured to forward any request he can't
satisfy to the 3 company nameservers using a round-robbing 
algorithm and cache the data till TTL ends (usually 2 days)

>I would try to do something about that /etc/hosts file, but that is really
>not going to help much.  I think what you should do is what Leslie
>make the machine a secondary name server.  Here is a useful link for you:

i'll read it but i don't think it will tell me anything 
new about tcp/ip or dns and name-resolution strategies

>from: Michael Seibold
>We once had some problems when netview tried to lookup ip-addresses 
>which were not in the /etc/hosts and not in the nameserver configured 
>in resolv.conf, so this nameserver had to ask another nameserver which 
>was not responding. As a result netmon was stuck and no status changes 
>took place (icons remained red, new icons remained blue  etc.)

thats why we use a caching-nameserver with 3 other dns-servers behind it
which all have the same name-database (this is throughly tested)

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