how to identify server authentication errors?

I recently inherited a server setup from the previous system admin, and I've been trying to diagnose and solve unresolved problems. I have a MacMini server that's hooked up to a raid disk, and I'm using apple server to administer the network.
I am now getting an error message that I suspect has something to do with how the network sharepoint has been set up, but I have no idea how to resolve the issue. The repeated error logs look like this:

Jul 6 17:28:03 srp003625srs.mydomain digest-service[49708]: digest-request: uid=0

Jul 6 17:28:03 srp003625srs.mydomain digest-service[49708]: digest-request: init request

Jul 6 17:28:03 srp003625srs.mydomain digest-service[49708]: digest-request: init return domain: SRP003625SRS server: SRP003625SRS indomain was: <NULL>

And every once in a while I get one of these:

Jul 6 17:29:53 srp003625srs.mydomain sshd[50801]: error: PAM: authentication error for root from 43.255.149.55 via 131.73.34.5

Jul 6 17:29:53 srp003625srs.mydomain sshd[50801]: Received disconnect from 43.255.149.55: 11: [preauth]

Jul 6 17:29:53 srp003625srs com.apple.xpc.launchd[1] (com.openssh.sshd.32CC706A-D013-4099-845A-99EE902B2558[50801]): Service exited with abnormal code: 255

On a side note, the file sharing works between the server and the clients, but the spotlight search doesn't seem to. I'm not sure if this is related or not, but I think that it has something to do with how the server directories are being shared over AFP/SMB. I'm very new to server administration and especially to the world of OSX, so forgive me if I'm totally off base.

I know these errors are vague, but are they indicative of anything in particular that I should look for?

Note: I intentionally made the IP and domains garbage, just in case someone suggests that's the problem.