ISA Server 2004/2006 Troubleshooting: Adding Replica Configuration Storage Server Error 0x80072108

I was working on a case recently where when the admin was trying to add Replica Configuration Storage server to his Array of 1 CSS (Configuration Storage Server) and two firewall nodes, it was failing with the following error:
 
Setup failed to install ADAM in replica mode Error Code : 0x80072108, The source server is currently rejecting replication requests

Troubleshooting

I made sure that this server was part of the replication storage server computers group in the enterprise policies. Replication is allowed and it's also part of array members in system policies.

The Error message "The source server is currently rejecting replication requests" and Error code 0x80072108 which as per err.exe provided following details

This suggested that the current Configuration Storage Server was rejecting the replication requests, so in order to find out why it was rejecting the replication requests we went to Configuration Storage Server and opened up command prompt and went to c:\windows\ADAM path and did the following:

First we ran the repadmin /options localhost:2171 command that displays replication settings (which shows up in the current DSA options which are set.)

Root Cause : In this case we found that inbound and outbound replication was disabled for the ADAM database.

Reference: http://technet.microsoft.com/en-us/library/cc783692(WS.10).aspx

Resolution

Then enabled both inbound and outbound replication on the ADAM database using the commands shown below. After that we ran repadmin /options localhost:2171 again and now DSA options were showing none as shown below.

After enabling replication, we again started installation on the server we wanted to add as replica CSSto, and this time we were able to add it successfully.