A cluster is a group of servers or nodes that work together to provide high availability, scalability, and load balancing for applications and services1.

Network latency is the time it takes for a packet of data to travel from one point to another on a network2. It is usually measured in milliseconds (ms) and can be affected by various factors, such as distance, bandwidth, congestion, and routing2.

The maximum network latency allowed between peers in a cluster depends on the type and configuration of the cluster, as well as the application and service requirements. Different cluster solutions may have different latency thresholds and recommendations for optimal performance and stability345.

one of the common cluster solutions that has a maximum network latency requirement is the Windows Server Failover Clustering (WSFC)3. WSFC is a feature of Windows Server that enables servers to work together to provide continuous service for applications and services, such as SQL Server, Exchange Server, and Hyper-V3.

According to the Microsoft documentation, the maximum network latency allowed between peers in a WSFC cluster is 100 ms one way3. This means that the round-trip latency between any two nodes in the cluster should not exceed 200 ms. This requirement applies to both the private and public network connections between cluster nodes, and is based on the assumption that the network is reliable and stable3.

The other options are incorrect because:

A. 30 ms total is too low for a realistic network latency requirement between peers in a cluster. It is unlikely that any network can consistently provide such a low latency across different locations and conditions2.

B. 300 ms total is too high for a network latency requirement between peers in a cluster. It is likely that such a high latency would cause performance degradation, timeouts, and failures for applications and services that rely on the cluster2.

D. 150 ms one-way is also too high for a network latency requirement between peers in a cluster. It would imply a round-trip latency of 300 ms, which is above the threshold for WSFC and other cluster solutions345.

References := 1: What is a Cluster? 2: What is Network Latency? 3: Windows clustering and geographically separate sites 4: Cluster Network Latency - Troubleshooting Guide 5: Support Policies for RHEL High Availability Clusters - Cluster …