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Re: netmon and /etc/hosts ?

To: nv-l@lists.tivoli.com
Subject: Re: netmon and /etc/hosts ?
From: Ray Schafer <schafer@tkg.com>
Date: Thu, 15 Jun 2000 14:28:47 +0000
REIBENSCHUH Alfred wrote:

> ok, i have to correct the information about our setup:
>
> we have a caching-only bind running on the loopback interface
> which uses round-robbing to query our 3 company dns
> and the /etc/netsvc.conf specifies local,bind as resolv order

Alfred,
Assumptions:

  1. Originally you said that you were blocked in some system calls that took
     1 to 2 mins.  I assume you were talking about the gethostbyaddr() calls.
  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 with
sufficeint memory to suck up a large /etc/hosts file is going to take 1 to 2
minutes to parse it.    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 you
are running named, and /etc/resolv.conf has the nameserver set to 127.0.0.1?

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 suggested:
make the machine a secondary name server.  Here is a useful link for you:

http://www.rs6000.ibm.com/doc_link/en_US/a_doc_lib/aixbman/commadmn/tcp_nameres.htm

(If the above appears on two lines it wrapped)

>
>
> mfG. Alfred Reibenschuh
> INFORMATIONSTECHNOLOGIE AUSTRIA GMBH
> TELEKOMMUNIKATION
> Networkmanagement
> A-1020 Wien, Lassallestrasse 5
> T: ++43-1-21717-58947
> F: ++43-1-21717-58979
> E: alfred.reibenschuh@it-austria.com
>
> -----Original Message-----
> From: lclark@US.IBM.COM [mailto:lclark@US.IBM.COM]
> Sent: Thursday, June 15, 2000 3:15 AM
> To: NV-L@tkg.com
> Subject: Re: [NV-L] netmon and /etc/hosts ?
>
> The conventional wisdom is that when the hosts file gets too big,
> you ought to use a DNS, and to keep that responsive, you ought to
> put a secondary nameserver right on the Netview server. If the large
> hosts file contains names you don't need, you could of course prune it.
> I know some customers shove a corporate hosts file around to all
> systems nightly. Of course with a box that big, it's probably just the
> names you need!
>
> Cordially,
>
> Leslie A. Clark
> IBM Global Services - Systems Mgmt & Networking
> Detroit
>
> ---------------------- Forwarded by Leslie Clark/Southfield/IBM on
> 06/14/2000 09:07 PM ---------------------------
>
> Ray Schafer <schafer@tkg.com>@tkg.com on 06/14/2000 02:01:50 PM
>
> Please respond to IBM NetView Discussion <nv-l@tkg.com>
>
> Sent by:  owner-nv-l@tkg.com
>
> To:   IBM NetView Discussion <nv-l@tkg.com>
> cc:
>
> Subject:  Re: [NV-L] netmon and /etc/hosts ?
>
> REIBENSCHUH Alfred wrote:
>
> > Hi !
> >
> > the machine      : ibm-rs6000 s7a 4-way 8gb memory 9gb swap 72gb disks
> > the system       : aix 4.3.2
> > the program      : tivoli/netview 6.0a
> > the configuration: no DNS, a well established /etc/hosts (6000 lines
> plus)
> >
> > on a " ovstart netmon ; netmon -M 53 " it takes hours
> > to get something other into the trace-file than
> > "event suppression installed"
>
> This is something to check out before you attempt to attack the problem by
> changing /etc/hosts:
>
> Be sure that you do not have an /etc/resolv.conf file.  If you have one,
> and
> especially if you have an entry to a nameserver in there, this could
> account
> for the delay: it will cause the systems resolver routines to query the
> nameserver before it looks in /etc/hosts.  It has to wait for an answer
> from
> the nameserver first.  AIX resolver routines will, (unless you tell it
> otherwise through /etc/netsvc.conf or the NSORDER environmental variable)
> use  DNS first IFF /etc/resolv.conf exists.
>
> --
> Ray Schafer                   | schafer@tkg.com
> The Kernel Group              | Distributed Systems Management
> http://www.tkg.com
>
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>
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--
Ray Schafer                   | schafer@tkg.com
The Kernel Group              | Distributed Systems Management
http://www.tkg.com


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