dns replies differ in src IP from query's dst IP (Bug?)

Guy Pazi guypazi at netvision.net.il
Thu Nov 22 11:26:25 UTC 2001


Thanks Mark and everybody else,
Good news this time.
Guy

> -----Original Message-----
> From: marka at isc.org [mailto:marka at isc.org]On Behalf Of
> Mark.Andrews at isc.org
> Sent: Thursday, 22 November, 2001 1:13 PM
> To: Guy Pazi
> Cc: Alex.Madden at Sun.COM; bind-users at isc.org
> Subject: Re: dns replies differ in src IP from query's dst IP (Bug?)
> 
> 
> 
> > Hi Alex,
> > 
> > Is it considered bad configuration? 
> 
> 	Bad (lazy) implementation would be a better description.
> 	On all modern stacks that I am aware of it is possible to
> 	get correct behaviour.
> 
> > Do you know how common is out there?
> 
> 	It's rare.  Most cases you see are where people are running
> 	really old nameserver on really old OS versions.  BIND was
> 	fixed with the 4.9.3 released (1995/12/31).
> 
> 	Mark
> > 
> > Thanks 
> > Guy
> > 
> > > -----Original Message-----
> > > From: am134452 at ms-egmp02-01b.UK.Sun.COM 
> > > [mailto:am134452 at ms-egmp02-01b.UK.Sun.COM]On Behalf Of Alex Madden
> > > Sent: Wednesday, 21 November, 2001 4:12 PM
> > > To: guypazi at netvision.net.il
> > > Subject: RE: dns replies differ in src IP from query's dst IP (Bug?)
> > > 
> > > 
> > > What happens is that the DNS server has more than one IP 
> address, and is
> > > running the nameserver on a secondary IP address. It recieves 
> the query
> > > on the secondary IP, and replies through its primary IP.
> > > 
> > > In extreme cases (with multihomed hosts for instance) you can 
> even see a
> > > reply from a different address space.
> > > 
> > > Regards,
> > > 
> > > Alex
> > > 
> > > --
> > > Alex Madden - Remote Administration Centre Engineer - SunUK
> > > Phone - (01252)423490 / x23490
> > > E-mail - alex.madden at sun.com
> --
> Mark Andrews, Internet Software Consortium
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org
> 


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