should i restart BESclient service after migration from an old BES server to a new one using the same masthead file and backup/Restore configuration files?
I’m assuming from this that you are overwriting the masthead with the one from the new server. If so, then yes, you do need to restart the client service.
no i’m using the same old masthead
I see you have two thread for the same issue.
If you’re using the same masthead then you will not need to restart the client. The clients will need time for DNS propagation if you’re using a DNS aliias.
All the migrations I have done where the IP of the root serer changes, I have our DNS teams reduce the TTL on the DNS record to 5 or 15 mins in advance of the migration so clients update their DNS cache for the server as quickly as possible.