Cannot Replicate after upgrading domain functional level

Parent and child domain. Parent domain (forest) still in domain functional level 2003. However, child domain i just updated to domain functional level 2008 R2. Now replication is not working. I believe the issue is dns, but i do not know what could be different the names have not changed? This is a two way transitive trust between domains.
Frequent messages from dcdiag dns, are
no DNS RPC connectivity (although i have tried restarting dcom, netbios and frs)
Also in event viewer many 13508 errors
Any help is greatly appreciated thank you.
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From Parent Domain DC, try to connect to ADUC of child domain and check if it allows you to connect, if not please check DNS records
Upgrading functional level has nothing to do with replication.
Replication problem must be there already, can you please check below
What is the name resolution method between parent and child domain ?

Parent domain should have dns delegation in parent dns zone ( pointing to child domain or secondary zone pointing to child domain dns zone
Also child domain must have conditional forwarder \ secondary zone pointing to parent dns zone

Once your name resolution is working correctly, your replication should work correctly
mrbayItAuthor Commented:
hi mahesh, i agree with your logic however the data shows differently. Everything was replicating fine, we add student accounts every day, the moment replication stopped was the moment i upgrade domain functional level. Which is what i am trying to unmask now. do you have any specific instructions i can follow to try and troubleshoot
What you are trying to replicate, parent domain have his own domain directory partition and child domain also has separate domain directory partition
Only configuration and schema partitions get replicated

Why \ How you get \ feel that replication is stopped

Please run repadmin /showrepl on parent DC and child DC to ensure AD replication is working or not?

Also is DNS is setup correctly?
Are you able to resolve parent and child domains correctly with nslookup?
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mrbayItAuthor Commented:
i can correctly resolve parent and child domains, but honestly all that i am trying to replicate right now is amongst DC's in the child domain. Not even looking into replication between child and parent
Really I don't see any problems with functional levels

Can you please post dcdiag /v and repadmin /showrepl output on child DCs ?
mrbayItAuthor Commented:
issue resolved

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Not sure what you mean by reenable replication ?

Raising functional level will not stop AD replication,

Can you explain what exact issue you have faced please?
mrbayItAuthor Commented:
after the upgrade replication froze, the pdc went into a protective state. i had to run these commmands from pdc
                                   § repadmin /options <DC NAME> +DISABLE_OUTBOUND_REPL
                                    § repadmin /options <DC NAME> -DISABLE_OUTBOUND_REPL
                                   § repadmin /options <DC NAME> +DISABLE_INBOUND_REPL
                                    § repadmin /options <DC NAME> -DISABLE_INBOUND_REPL

and that resolved it
mrbayItAuthor Commented:
i figured it out, had to reenable replication
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