3269
Active Directory Global Catalog over LDAPS (TLS)
Microsoft Global Catalog LDAP over SSL
What is port 3269?
Port 3269 is the TLS-encrypted version of the Global Catalog LDAP port (3268). It provides secure cross-domain directory queries in multi-domain Active Directory forests. Always prefer this over port 3268 to protect authentication data and directory contents in transit.
Quick checks
$
nc -zv example.com 3269
$
nmap -p 3269 example.com
$
telnet example.com 3269