Hello All, Yes I know there will be questions like why? but if someone could share their thoughts on IP address and ports it would be most welcome. Trying a distributed transaction across a linked server. The source server is FCI SQL 2008 r2 EE sp2 The linked server is an availability group on FCI SQL 2012 EE sp2. We have restricted the ports for RPC in the registry. Should we be opening the firewall/ports for the IP address of source server? Source server DTC? linked server AG listener? linked server? linked server DTC? Thanks for any info.