Uncover DC Agent communication issues

Before you begin

In order to identify users, DC Agent uses DNS or NetBIOS to identify domains and domain controllers in the network. DC Agent may be unable to identify domain controllers if there are network communication problems, or DNS or NetBIOS configuration problems.

To identify these issues:

Steps

  1. Open a command prompt or Windows Powershell on the DC Agent machine.
  2. To verify that the DC Agent machine can see all required domains, use the net view command:
    net view /network
  3. To check for DNS issues, use the nslookup command.

    For example, to find out if DNS resolves the hostname “testmachine1”:

    nslookup testmachine1

    If the DNS lookup succeeds, the result looks something like this:

    Server: testdns.test.example.com
    Address: 10.56.1.4
    Name: testmachine1.test.example.com
    Address: 10.56.100.15
    Use a similar command to verify that a reverse DNS lookup will succeed for a dual-stack (IPv4 and IPv6) client with IPv6 address “::ffff:A.B.C.D”:
    nslookup ::ffff:A.B.C.C
    If the DNS lookup succeeds, the result looks something like this:
    Server: testdns.test.example.com
    Address: ::ffff:A.B.C.C
    If lookup does not succeed, make sure you have a reverse lookup zone for IPv6 in your DNS.
  4. If DC Agent is configured to use NetBIOS, attempt to telnet to a domain controller on port 139. If the telnet command is successful, you will see a blank screen. If unsuccessful:
    • A router, firewall, or other device may be blocking NetBIOS traffic.
    • NetBIOS may not be enabled, and the domain controller may not be listening on port 139. To check the status of the port, use the netstat command:

      Windows:

      netstat -na | find "139"

      Linux:

      netstat -na | grep 139