can not run cyradm from remote server .. realm gets appended to username

[ram]

On my cryus imap server , when I try login  from my localserver cyrus
login works 


But when I login from a remote server realm gets added autmatically ,
causing login to fail 


In my sasl logs I can see for a local connection
-----
saslauthd[21947] :do_auth         : auth success: [user=cyrus]
[service=imap] [realm=] [mech=pam]
saslauthd[21947] :do_request      : response: OK
------





For a remote connection 
-----
saslauthd[24011] :do_auth         : auth failure:
[user=cyrus at netcore.co.in] [service=imap] [realm=netcore.co.in]
[mech=pam] [reason=PAM auth error]
------


What can be seen simply is that the realm netcore.co.in is getting added
automatically. How can I avoid this