HP gethostbyaddr errors

[James Hall-Kenney]

> -----Original Message-----
> From: Mark.Andrews at nominum.com [mailto:Mark.Andrews at nominum.com]
> Sent: Monday, 17 April 2000 15:45
> To: James Hall-Kenney
> Cc: bind-users at isc.org
> Subject: Re: HP gethostbyaddr errors 
> 
> 
> 
> > All,
> > 
> > We have a customer who is having trouble with BIND 8.2.2-P5 
> on HP-UX 11.
> > 
> > They use router management software (Spectrum on Solaris) 
> that maps the
> > network topology and uses reverse resolution to determine 
> the device name of
> > the router.  Because they are monitoring multiple 
> interfaces on the router,
> > the name in the management software will change regularly.  
> To circumvent
> > this, we have created the reverse resolution entries to all 
> resolve to the
> > same name ie:
> >      
> >      Forward Resolution entries:
> >       
> >      interfacea        129600  IN      A       10.13.255.5 
> >      interfaceb        129600  IN      A       10.13.128.1 
> >      interfacea        129600  IN      A       10.13.130.1 
> >      
> >      Reverse Resolution entries:  (13.10.in-addr.arpa) 
> >       
> >      5.255       129600  IN      PTR     interfacea.ssi.govt.nz. 
> >      1.128       129600  IN      PTR     interfacea.ssi.govt.nz. 
> >      1.130       129600  IN      PTR     interfacea.ssi.govt.nz.
> > 
> > They have a different management product - HP Network Node 
> Manager running
> > on HP-UX 11.  For some reason, this host seems to want to 
> verify that the A
> > record matches the PTR.  We get a message in syslog: 
> >   gethostbyaddr : timcr100.ssi.govt.nz != 10.213.130.1
> 
> 	This message indicates that when gethostbyaddr did a reverse
> 	lookup on 10.213.130.1 it found the name was 
> timcr100.ssi.govt.nz.
> 	It then performed a forward lookup on timcr100.ssi.govt.nz
> 	and didn't find 10.213.130.1 as a valid address for
> 	timcr100.ssi.govt.nz.
> 
> 	This could be due to a error in the DNS 

   So you would consider the configuration discussed to be invalid as 
   the A records do not match the reverse records, even intentionally?

   James

>     or to a limitation in
> 	gethostbyname (called by gethostbyaddr) which limits the number
> 	of addresses to 35.
> 
> 	Mark
> 
> > 
> > As this box is managing over 2,000 addresses, it is doing a 
> lot of name
> > resolution and filling up the syslog on the host very 
> quickly.  Note that
> > the management works OK.  The customer called HP to get 
> them to resolve the
> > problem and HP are saying that the DNS configuration of 
> mismatched A and PTR
> > records is "broken".  The engineer has quoted from page 64 
> of O'Reilly DNS &
> > BIND:
> > 
> >      "To state as a general rule: if a host is multihomed 
> create an address 
> >      record for each alias unique to one address. Create a 
> CNAME record for 
> >      each alias common to all the addresses"
> >      
> > Of course, this method doesn't provide for a single name 
> per device on the
> > Spectrum management server.
> > 
> > My questions:
> > 1.  Is the described method considered to be a broken 
> implementation?  I
> > haven't seen any explicit statements in the RFC's that 
> state that the PTR
> > MUST match the A record.
> > 2.  Any suggestions on how to work around this other than 
> force a change
> > with HP?
> > 
> > TIA
> > 
> > J.
> > 
> > James Hall-Kenney
> > Sytec Resources Limited
> > 	
> > 
> > 
> > 
> > 
> --
> Mark Andrews, Nominum Inc. / Internet Software Consortium
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: +61 2 9871 4742                 INTERNET: 
> Mark.Andrews at nominum.com
>