What would cause an Active Directory connection attempt to a workstation?

I'm trying to troubleshoot a freezing issue with our git server.

We're running Atlassian Stash on a dedicated Windows Server 2012 R2 Standard virtual machine.

The server will sometimes (a few times each week) appear to freeze for a few minutes. The freeze seems to only impact connected git clients; other activities on the machine are running fine. We can still use remote desktop to access the box fine; task manager shows little CPU activity and negligible amounts of disk and network IO.

We have noticed that the machine is making an outbound LDAP connection to a workstation - not to any of our Active Directory domain controllers, but to a laptop. Obviously the laptop won't respond, so the connection hangs until it times out. As soon as the timeout expires, normal git service is resumed. At least, until the next time. We've verified that the network connection is originating with Tomcat, the application host for Stash.

What would cause this server to try establishing an LDAP connection to a machine that isn't an Active Directory controller?

The directory services configuration for Stash lists only a local Active Directory domain controller, but we notice there are multiple outbound connections to other valid domain controllers as well. How does the machine find out about these other domain controllers? And might that mechanism explain why it's trying to talk to a laptop?