“If you are running WebSphere MQ 7.5.0.0 and you get MQ Reason Code 2009 for Client Channel Applications then there may be a change you can make to prevent the MQRC 2009. Often the problem is intermittent.
In the qm.ini file add the following lines :-
TCP:
DNSLookupOnError=No
The actual problem was introduced in 7.5.0.0. There is a fix for the problem in a future fix pack. But you may get round the problem with the qm.ini change above. “