DNS, DHCP or what?

[Kevin Darcy]

Some DHCP servers have the ability to automatically update DNS when they give out a lease. Others do not.
You should talk to the DHCP administrator to see if this is possible with your DHCP server.

Your "ping" problems appear to be unrelated. DNS is involved only in mapping names to addresses or other
types of data (for these purposes, mapping an address to a name -- so-called "reverse DNS" -- is actually
mapping a special kind of name to another name). Once name resolution is done, DNS is out of the picture.
So if you're sending packets from the right address to the right address, and not getting a response, then
DNS would appear to be uninvolved. Talk to your network and/or firewall staff.

Sorry, I can't help with "Network Neighborhood" or SMB-related stuff, or "pump" (whatever that is), since
I'm unfamiliar with those areas.


- Kevin

Milt Tinkoff wrote:

> I'm running RedHat 6.1 on a pc connected to a network of Windows boxes
> and can't seem to troubleshoot this problem.  DNS (through pump) sort of
> works, but my own hostname can't seem to be resolved (gethostbyname
> always fails).
>
> I don't understand enough about how all these protocols work to know
> what's going wrong.  DHCP is definitely giving me IP addresses, but how
> is it (and/or the nameservers) supposed to know what my hostname is?  I
> tried passing it to pump through the -h argument, but there was no
> difference.
>
> DNS works since I'm still connected to the internet (web browsers,
> etc. work), but ping can only resolve external hostnames and doesn't
> receive packets.
>
> What DOES work:
>
> The local DHCP server is successfully giving me floating IP addresses.
>
> ping 127.0.0.1
> ping localhost
> ping myIPaddress
> ping myIPaddress (from another machine on the LAN)
> ping otherIPaddressOnLAN
> ping otherHostOnLAN
> ping otherHostOnLAN.mydomain.com
> (all work normally)
>
> hostname
> domainname
>
> Mounting shares (using smbmount) from other machines on the LAN.
> Web browsers, newsreaders, ssh, etc. all work.
> nslookup on anything but myIPaddress or myhost
>
> What DOESN'T work:
>
> ping myhost
> ping myhost.mydomain.com
> (unknown host)
>
> ping mydomain.com:
> PING mydomain.com (correct IP address) from (my IP address provided by DHCP) : 56(84) bytes of data.
> but no packets are received
>
> ping www.yahoo.com (or any other external machine):
> PING www.yahoo.akadns.net (216.115.105.2) from (my IP address provided by DHCP) : 56(84) bytes of data.
> but no packets are received
>
> nslookup myhost
> nslookup myhost.mydomain.com
> (Non-existent host/domain)
>
> The linux box doesn't show up in Network Neighborhood of other computers
> on the local network.
>
> Any ideas as to what could cause this set of symptoms?
>
> It seems to me that the nameservers just aren't being informed (by
> DHCP?) that my IP address is associated with my hostname.
>
> Thanks for any help.
>
> -milt