The solution requires adherence to SnapMirror Synchronous (SM-S) network latency constraints. The round-trip time (RTT) for SM-S must be less than 10 ms.

The link between Cluster 1 and Cluster 2 has an RTT of 7 ms, which is suitable for SM-S. The link between Cluster 1 and Cluster 3 has an RTT of 29 ms, which exceeds the 10 ms limit, making SM-S unsupported. Therefore, any replication to Cluster 3 must be asynchronous.

Option A (cascade) and Option C (fan-out) both correctly propose using SM-S for the low-latency link to Cluster 2 and asynchronous SnapMirror for the high-latency link involving Cluster 3. Both are valid and supported three-way disaster recovery topologies in ONTAP.

B: This option is incorrect because SnapMirror Synchronous is not supported for the link between Cluster 1 and Cluster 3, as the 29 ms RTT exceeds the 10 ms maximum.

D: This option is incorrect because a cascade using SnapMirror Synchronous for the long-distance link from Cluster 2 to Cluster 3 is not feasible due to the high RTT.

1. NetApp, TR-4742: SnapMirror Synchronous Deployment and Best Practices Guide for ONTAP 9.5 and Later.

Page 9, Section: Network requirements: "The round-trip time (RTT) between the clusters must be less than 10ms." This confirms why the link to Cluster 3 cannot use SM-S.

Page 10, Section: Supported topologies: This section explicitly describes and illustrates both fan-out and cascade topologies. It states, "A source volume can be replicated to a maximum of four destination volumes. The replication can be a mix of SnapMirror Synchronous and SnapMirror asynchronous relationships" (validating option C) and "A SnapMirror Synchronous relationship can be cascaded to a SnapMirror asynchronous relationship" (validating option A).

2. NetApp ONTAP 9 Documentation Center, Data protection using SnapMirror Synchronous relationships.

Section: Requirements for synchronous replication: "The network latency between the clusters must be less than 10 milliseconds round-trip time (RTT)." This reinforces the core requirement used in the analysis.

Section: SnapMirror cascade and fan-out relationships for data protection: This document details how a source volume can be part of both a fan-out configuration (replicating to multiple destinations) and a cascade configuration (A->B->C), including mixed synchronous and asynchronous modes.