HP gethostbyaddr errors

Mark.Andrews at nominum.com Mark.Andrews at nominum.com
Mon Apr 17 03:45:27 UTC 2000


> 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 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



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