Geo Replication: Membership and Routing

Distinguish fixed membership, available capacity, and quorum intersection.

Get every question correct to pass this checkpoint. You can review feedback, revise your answers, and submit again.

1. Eight configured replicas split into two disconnected groups of four. Each side can reach its own group and uses R=W=3. What should both planners report?

Select one answer.

ok, because three is a majority of the four reachable replicas insufficient-read, because reads require all eight replicas ok on the side with lower regional latency unsafe-quorum, because the response sets need not intersect within the configured eight

2. Configured N=7 and W=4. What is the smallest positive R satisfying R+W>N? Enter one integer.

3. A seven-member configuration uses R=W=4, but only three members are reachable. Which result follows?

Select one answer.

Remove unreachable replicas from configured N, then return ok Reduce both thresholds to three and return ok The intersections are safe by size, but the routes are infeasible, so return insufficient-read Return unsafe-quorum with complete read and write routes

4. All regions are healthy: a has 1 replica at latency 5, b has 2 at latency 10, and c has 3 at latency 50. What modeled latency does the three-response read route have? Enter one integer.

5. For N=5, R=1, W=3, both routes are feasible. Which safety condition is missing?

Select one answer.

A sorted region-name list before any latency comparison Read/write intersection: one reader may contact a replica outside a completed three-replica write set Write/write intersection, because three is never a majority No condition is missing because the selected routes may happen to overlap

6. A plan has status ok. What additional evidence is needed before claiming a linearizable distributed database?

Select one answer.

A protocol that orders writes and chooses valid read versions, with a safe membership-change procedure Equal regional latencies At least two regions in every selected route regardless of replica count No additional evidence; cardinality proves the entire protocol

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