why clients connected to certain AP(zf-2741) are not getting IP address some times

[satish_kumar_ka]

i found so many times that clients connected to certain AP were not getting IP address. what would be possible reasons behind it.

Regards,
kumar

[keith_redfield]

DHCP address pool is exhausted (too many clients, overly long reservations)
DHCP server congested (is it the AP, a ZD, a 3rd party?)
High interference
AP restarting/crashing (check the logs)
poor L2 connectivity to DHCP server (check switch)
Faulty AP (swap with another)
....

There's more but that's a good start.

[jeff_roback]

I'd start with L2/L3 connectivity. Check VLANs and ip-helper DHCP forwarding.
Try giving a client a static IP address, connect to that AP and see if they can ping the DHCP server's IP address.