How to check quickly AD replication issues in a forest?

Used the command Repadmin /replsummary summarizes the replication stateandcollecting information such as replication deltas and replication failures.And also run the repadmin /showreps or repadmiin /showrepl command to verify the replication status.

at first you have to check active directory sites and check the replication connections, and you can download the active directory replication status tool to check the replication status. 

 then check the network connectivity between the domain controllers after that force the replication using repadmin tool

Repadmin.exe

a Microsoft tool to check AD and AD ploicy replications ststus between AD servers

repadmin / syncall will give you summerize report.

the site manager mmc console should be your way begin to troubleshooting and managing replication.

from there not only can you see the connection objects but also change settings, attributes and even force the replication with a single click.

in some cases you have to delete and recreat the replication connection objects, situation like where DNS or GC is unsynch or giving trouble.

you would also want to make sure that you have IP connectivity between the DCs and ensure that all ports needed for DCs to communicate are open i.e. there is no firewall between them blocking communication.

there are many other bulitin tools and ways of debugging the issue as well.

thank you

Use the command Repadmin /replsummary.

You can execute repadmin /syncall /AdeP for force replication. You may use repadmin /replsum or repadmin /showreps or repadmiin /showrepl command to verify the replication status.

The eaiset and quickest replication check commands, from the CMD:

Repadmin /replsum

Repadmin /showrepl

simple and efficient :)