I have a CUCM v9, connected and synchronized with Microsoft LDAP correctly. When I hit the Directory Button for the first time, It take a long time to respond to my request, and after that I can get response quickly. I'm asking if there is something wrong, or it's a normal behaviour from CUCM?
No, are you using IP or hostname?
What's the CPU utilization on the server?
What's between the phone and the CUCM server?
And thank you for your feedback, in my case, I use IP addressing between CUCM and all the endpoints, the CPU is normal. I don't know if the CUCM try to download the LDAP directories after every first request, or there is another issue that cause this delay.
Sounds like DNS resolution is taking long time, best way to prove it would be to put a PC with wireshart on the back of the phone and trace the request and look for DNS packets.