AD Replication - When are second site links used?


  • Hi,

     I have an RODC in a DMZ network which is struggling to replicate with other DCs outside of its site, a repadmin /replsummary shows replication errors with IDs 1722 and 58.

     My DMZ site has 2 site links, link A has a site cost of 10 and link B has a site cost of 50. I've done some port scanning and the DMZ firewall is blocking the below ports to my primary site over site link A:

    - TCP 139, 636, 3269
    - UDP 138

     My question is when is the second site link used? I believe that the DMZ AD site will try to replicate over site link A, but when will it use site link B? What constitutes a site link failure? Would the ports above being closed denote a site link failure and then force AD replication over site link B?


    IT Support/Everything

    Friday, March 31, 2017 3:04 PM

All replies