I followed the instructions given in this following IBM documenation to enable "automatic client reroute" to a database which is HADR enable.

Configuring automatic client reroute and High Availability Disaster Recovery (HADR) - IBM DB2 9.7 for Linux, UNIX, and Windows

My HADR is working fine, however when secondary database takesover as Primary, and if I try to connect, my connection is not not getting rerouted. I see following error

SQL1776N The command cannot be issued on an HADR standby database. Reason
code = "1".

Any suggestions would be of great help.

Thanks,
- G's

if alternate server is setup correctly - db2 clients will get this info after first connect
db2 list db directory
if using java type4 connection, you have to specify alternate server/port as options

Thanks Guy - it worked actually I while defining ALTERNATE SERVER I specified wrong port number and due to which it was connecting to some other instance which was not running