Cisco Routers, NAT and DNS...

[Simon Waters]

Marc.Thach at radianz.com wrote:
> 
> I reckon the 99% "general way" that people use NAT is this: simple NAT or
> NAPT for the purpose of putting more IP clients onto the Internet than they
> have available registered address space.

That was the conclusion I came to by reading more Cisco
docs, but I'm keen to know more.

> BTW the doc that Simon linked to:
> http://www.cisco.com/warp/public/cc/pd/iosw/ioft/ionetn/tech/emios_wp.htm
> describes twice-NAT, which is more complex than simple NAT (and IMO best
> avoided for general Internet connectivity).

Yes, the document is aimed at how to quickly connect
networks with overlapping IP address spaces, so if two sites
using 10.0.0.0, and both have a DNS, and renumbering is a
major job.... To me this would seem like the main occaison
for needing to rewrite DNS packets, certainly I can't see
people being overkeen to do this for ordinary Internet
connections, not least as it doesn't handle zone transfers
so all your DNS servers would presumably be behind one
router.

Anyone any experience in using this in anger care to
comment.