Which latency figure is the cross-region latency range that informs decisions about data replication and edge caching?

Which latency figure is the cross-region latency range that informs decisions about data replication and edge caching?

• A. Sub-1 ms latency within a single availability zone.
• B. 1-2 ms latency across availability zones in the same region.
• C. 10-20 ms latency for cross-region communication.
• D. 50-150 ms cross-region latency.

Answer: (D)

Cross-region latency reflects the WAN delay between data centers in different regions, and it guides how you design replication and edge caching. When the latency between regions is in the 50–150 ms range, you generally cannot rely on synchronous replication across regions because the round-trip time is too long to keep regional copies perfectly in sync in real time. Instead, you design for eventual consistency with asynchronous replication, accepting some lag between regions. Edge caching becomes essential at this scale: you place caches closer to users so their requests are served from nearby locations, masking the higher cross-region latency. You also tailor cache invalidation and TTLs to account for the delay in propagating updates across regions. In short, 50–150 ms is a realistic cross-region figure that shapes decisions about how aggressively you replicate data and how aggressively you rely on edge caches to meet latency goals. The other figures describe much smaller latencies applicable within a region or between closer zones, which don’t capture the typical challenges and design choices faced when data must traverse regional boundaries.

Cross-region latency reflects the WAN delay between data centers in different regions, and it guides how you design replication and edge caching. When the latency between regions is in the 50–150 ms range, you generally cannot rely on synchronous replication across regions because the round-trip time is too long to keep regional copies perfectly in sync in real time. Instead, you design for eventual consistency with asynchronous replication, accepting some lag between regions.

Edge caching becomes essential at this scale: you place caches closer to users so their requests are served from nearby locations, masking the higher cross-region latency. You also tailor cache invalidation and TTLs to account for the delay in propagating updates across regions. In short, 50–150 ms is a realistic cross-region figure that shapes decisions about how aggressively you replicate data and how aggressively you rely on edge caches to meet latency goals.

The other figures describe much smaller latencies applicable within a region or between closer zones, which don’t capture the typical challenges and design choices faced when data must traverse regional boundaries.