Which two components are required for a highly available CUCM cluster?

Which two components are required for a highly available CUCM cluster?

• A. Publisher
• B. Publisher and Subscriber
• C. Subscriber and Expressway
• D. Publisher and Unity

Answer: (B)

High availability in CUCM is built around a two-node cluster that includes a Publisher and at least one Subscriber. The Publisher holds the master database and is the source of truth for configuration and call-control data. The Subscriber maintains a replica of that database and provides redundant call-processing capability, so the cluster can continue handling calls if the Publisher experiences issues. Expressway and Unity serve separate roles—Expressway for external collaboration connectivity and Unity for voicemail—and are not required to achieve core CUCM HA. Hence, the minimal highly available CUCM setup is a Publisher paired with a Subscriber.

High availability in CUCM is built around a two-node cluster that includes a Publisher and at least one Subscriber. The Publisher holds the master database and is the source of truth for configuration and call-control data. The Subscriber maintains a replica of that database and provides redundant call-processing capability, so the cluster can continue handling calls if the Publisher experiences issues. Expressway and Unity serve separate roles—Expressway for external collaboration connectivity and Unity for voicemail—and are not required to achieve core CUCM HA. Hence, the minimal highly available CUCM setup is a Publisher paired with a Subscriber.