#DNS

1 guide

Diagram-style cover: a source domain controller reaching a target DC through DNS, the RPC endpoint mapper on port 135, and the dynamic RPC port range

How to Fix Active Directory Replication Error 1722: The RPC Server Is Unavailable

A practical, step-by-step guide to diagnosing and fixing Active Directory replication error 1722 — the RPC server is unavailable — from DNS to firewall to RPC ports.

MCSA Guru Team May 20, 2026 7 min read