problem with reverse lookup of private IP

[Kevin Darcy]

Sally Wong wrote:

> Hi,
>
> we have had problem to ftp or to telnet from PC that uses a private
> IP.  We use to have this problem intermittently, and this consistently
> happens to the PC with a private IP.  There is no problem when coming
> from a public IP.  Our DNS server crashed last week, ever since it
> came back on, we have heard a lot more of such kind of problem.
>
> However, sometimes if we added the private IP address into the
> /etc/hosts file, this problem would go away.  Looks to me this is a
> reverse lookup kind of problem.  Do anybody out there know of such a
> case?
>
> many thanks
>
> Sally
>
> does anybody know if any strange things happen when rfc1918 is in the
> picture?

Yes, "strange" things happen when you don't have the appropriate RFC 1918
reverse zones set up in your DNS infrastructure. The "strange" thing is
that your nameserver(s) try to resolve those addresses from the
"blackhole" servers, which are perpetually overloaded.

If you have the appropriate zones set up, then the problem would appear
to be local and you should look at the logs on the relevant servers to
see what the problem may be.


- Kevin