DNS & BIND working with NAT & PAT

SOLARlS at aol.com SOLARlS at aol.com
Tue Sep 21 21:29:49 UTC 1999


My backbone has proposed a routing and IP addressing issue to me.  I am a web 
hosting company.  They have suggested that I use NAT (Network Address 
Translation) and PAT (Port Address Translation).  With this method it is hard 
for me to see how DNS will work with these two things.

Here is an example:

NAT IS:

If you have an IP address that is 204.32.56.8 you can make thousands of 
addresses out of this one address by utilizing the 10 net (10.0.0.1 - local 
ip addressing).  Although with NAT alone it would cause limited access to 
sites on my network.  So I would then use PAT (port address translation) to 
make it possible for this to happen.

Here is an example of NAT and PAT together:

204.32.56.8:54321 = 10.0.0.8
204.32.56.8:54322 = 10.0.0.9
204.32.56.8:54323 = 10.0.0.10

What is confusing me is that the outside world of the Internet has to see 
real #'s which would be 204.32.58.8.  Meaning my DNS machines would have to 
resolve all sites to a real #.  So for an example if a request came in for 
abc.com and its real IP address according to the Internet is 204.32.56.8 but 
its local might be 204.32.56.8:54321 which is equal to 10.0.0.8 on the local 
network. 

****** MAIN CONCERN *******

******* How is DNS going to be able to distinguish between ports and requests 
when a router can't route a domain name.  It can only route an IP 
address?********

Greg


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