[plug] DNS name

The Thought Assassin assassin at sleepless.south.networx.net.au
Mon Jul 27 08:40:41 WST 1998

On Sun, 26 Jul 1998, Shackleton, Kevin wrote:
> I have a small problem I haven't figured out, on RH5.0 PCs.
> I have 2 of these on this LAN, which is a subnet of a statewide network.
> Both use the same name server, which is on another subnet.  Both can
> ping machines by name machines on the name server's subnet, but neither
> can ping the other by name on this LAN.  I don't know of any unix
> machines on any other subnet to try out - there are routers and things
> but they're not named AFAIK.

You don't say whether you can ping by IP number. Can you?
That will tell you whether it is a DNS problem or a routing problem.

> It appears that the name server is not learning of the names of the
> Linux machines.
Internet nameservers don't "learn" the names of machines. You need to tell
them explicitly.
WINS servers don't unless you have more than one network, or more than one
type of SMB client, or more then one type of SMB server.
Redhat should definitely be using DNS, not WINS.
> When I use tcpdump to track messages, a ping to the other machine
> produces the request "who has <gateway ip number>".  
That is probably an "address resolution protocol" packet. Arp is the
protocol used to determine the physical address of the ethernet card which
is answering to a particular IP. The machine is trying to find the
physical address of the gateway so it can send the DNS query through it.

> To me it suggests
> the machine is thinking that the gateway configuration is being treated
> as a string.  
Not sure what you mean by this, but IP addresses are always held
internally as numbers, including in the routing table.

> netstat -r though shows the destination "default" to have
> the correct gateway.
If it didn't have the right gateway, it wouldn't be trying to send a
packet through it :)

Can you give us more details as to the nature of the problem?
Use the "host" command (or look in the details of a ping) to see whether
you are able to resolve the various hostnames.
(each of the two machines, the gateway, and the DNS.)
Which of the four machines can you ping by IP _number_?

That ought to be enough info for us to work out the problem,


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