More Mac .local nonsense

Just when you thought it was safe to recommend .local again…

While I wasn’t expecting that Mac OS 10.4 would solve all the world’s problems, I was pleasantly surprised to find that Apple worked around their boo-boo related to the .local top-level domain multicast DNS lookups. Never in a million years would I have expected the problem to crop up with pre-Mac OS X. But it did.

I’ve got an old iMac that I’m integrating into my test network to have an OS 9 machine around for reproducing problems, etc. Right out of the gate, I’m not able to get Outlook 2001 to connect to my test Exchange server. I do a little more digging and find out, once again, it’s related to the .local namespace I have set up in my test lab.

Outlook, Internet Explorer, and MacTCP Ping all failed to resolve the name of my server in the .local domain. Accessing other systems outside of the .local domain work fine. So, out comes netmon to figure out what’s actually going on.

I started the netmon trace and used MacTCP Ping on the iMac to do some internal and external lookups. On the very first trace, I notice the problem. The DNS queries for systems outside the .local namespace are headed to my SBS server’s IP address on port 53, just like a good DNS lookup call should. All lookups for names in the .local namespace are going to an unusual address on port 5353. Yep, that’s multicast DNS, not traditional DNS.

I tried several tricks to force the Mac to do lookups only against the DNS server, but to no avail. I ended up falling back on using a HOST file on the Mac to get the .local lookups working. As it had been a while since I’d messed with host files on Mac OS 9, I hit Google and found this site ( http://www.g4tv.com/techtvvault/features/3428/Alternatip_Create_a_Mac_OS_9_Hosts_File.html ) which quickly got me through the host file creation process and got my Outlook connected on the next try.

I’ve got queries in to several groups to get confirmation on this, but I suspect it’s a problem related to Mac OS 9.2 only. I’m going to try to bring up a Mac OS 9.1 machine and test .local lookups from that OS, expecting that it will work as expected.

So, once again, I return to my stance of not using .local for an Active Directory internal domain name, recommending using .lan or .office instead. More information as it becomes available.