Re: Running public DNS server on iSeries

[Ken Sims <mdrg5003@xxxxxxxxx>]

Hi Neil -

> Have a customer switching ISP's from one who was providing DNS service to
> one who won't (because the latter has DSL and the former is only ISDN).
> They only have one system, the iSeries, behind a firewall.  I was
> wondering about running a DNS server on the iSeries for their public
> domain, and seting the firewall to forward DNS port 53 traffic to the
> internal address of their iSeries.  Is this possible?  (May be an issue
> there too in that the internal DNS address for their domain should resolve
> to a 192.168.x.x address, so maybe that's a showstopper right there).  I'm
> thinking I'd be better off signing them up with one of the free DNS
> service providers.

Running any kind of name or DNS server can be a real PITA.  Since any ISP 
should provide DNS servers for looking up other people's IP addresses, I 
assume that you are talking about name servers (the servers that tell other 
people what your IP address(es) are).  Unless you, or someone at your 
company, is experienced in running name servers, I strongly recommend that 
you use an outside service.

As has been mentioned, many registrars provide this free.  I prefer to use 
a third-party name server service that costs me $10/year/domain, but puts 
my information on seven different name servers on six different ISPs, in 
four different countries, on two different continents.

Returning an internal IP address to the outside world is an absolute 
no-no.  They wouldn't be able to use it to connect to you anyway.  If you 
can't configure your internal network to use the external IP address, then 
you must return different IP addresses internally and externally.

> Also, DNS on port 53 uses only TCP. not UDP - is that right?

No.  Other than zone transfers and such, DNS generally uses UDP unless the 
result is too large to fit in a UDP packet.

--
Ken
http://www.ke9nr.net/
Opinions expressed are my own and do not necessarily represent the views of 
my employer or anyone in their right mind.