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

[Mark_Andrews at isc.org]

> 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