hey, im trying to understand how to run remote x applications. now, my problem is that my boxes doesnt seem to find eachother. i try to xhost +hostName.domainName but it just returns "not a valid host". The computers are connected and can ping eachother so thats not the issue.
doing it locally on each box works(xhost +localHostName) so i figure it must have something to do with the domain name im using..im behind a router that provides a domain name, and i use dhcp to pass network info. but do i need to tell linux something else about the domain to be able to get this to work?

im lost

From the xhost man page:
Names
A complete name has the syntax ``family:name'' where the families are as follows:

inet Internet host (IPv4)
inet6 Internet host (IPv6)
dnet DECnet host
nis Secure RPC network name
krb Kerberos V5 principal
local contains only one name, the empty string

The family is case insensitive. The format of the name varies with the family.

When Secure RPC is being used, the network independent netname (e.g., "nis:unix.uid@domainname") can be specified, or a local user can be specified with just the username and a trailing at-sign (e.g., "nis:pat@").

For backward compatibility with pre-R6 xhost, names that contain an at-sign (@) are assumed to be in the nis family. Otherwise they are assumed to be Internet addresses. If compiled to support IPv6, then all IPv4 and IPv6 addresses returned by getaddrinfo(3) are added to the access list in the appropriate inet or inet6 family.

I think you need to add the 'family:' part to the name to add the site to the hosts list.

This will only provide rudimentary security. You may want to use ssh instead which would allow you to run applications remotely.