since F5 supports several distinct LDAP usecases (e.g. login to admin interface, using AD/LDAP auth in APM, using APM Keberos Contrained Delegation, etc.), it would be helpful to get more information what you trying to achive, how your configuration looks like and where you saw the related error message.
Hi @ahmedwerdany ,
Do you configure The DNS servers for F5 system ? you need to make sure that your F5 perform DNS resolution successfully.
Are There any firewalls between F5 and AD servers ?
if yes " you need to open (LDAP ports 389 udp and LDAPS port 636 TCP & udp)
> Also , I think you need authentication profile on your AD to identify F5.
Follow this KB to review your Configuration :