Operations Master Protocols
Operations masters use the same protocols as other domain controllers. The protocols that package the data sent to and from a domain controller are described in the following table.
Operations Master Protocols
| Protocol | Description |
|---|---|
| Lightweight directory access protocol (LDAP) | The primary directory service protocol that specifies directory communications. It runs directly over TCP/IP, and it can also run over UDP connectionless transports (UDP access is primarily used by the domain controller Locator process). Clients use LDAP to query, create, update, and delete information that is stored in a directory service over a TCP connection through the TCP port 389. AD DS supports LDAP v2 (RFC 1777) and LDAP v3 (RFC 2251). LDAP v3 is an industry standard that can be used with any directory service that implements the LDAP protocol. LDAP is the preferred and most common way of interacting with AD DS. |
| Remote procedure call (RPC) | Protocol for replication (REPL), domain controller management communications, and SAM-related communications. RPC is a powerful, robust, efficient, and secure interprocess communication (IPC) mechanism that enables data exchange and invocation of functionality residing in a different process. That different process can be on the same computer, on the local area network (LAN), or across the Internet. |
| Simple mail transfer protocol (SMTP) | Protocol for replication communications when a permanent, “always on” network connection does not exist between two domain controllers. SMTP is used to transport and deliver messages based on specifications in Request for Comments (RFC) 821 and RFC 822. SMTP can replicate configuration, schema, and global catalog replicas only (not writable domain data). |
For more information about AD DS protocols, see “How the Data Store Works.”