# Users can configure a shorter ``heartbeatFrequencyMS`` than the default to
# allow a smaller ``maxStalenessMS`` with replica sets.
---
heartbeatFrequencyMS: 1000  # 1 second.
topology_description:
  type: ReplicaSetWithPrimary
  servers:
  - &1
    address: a:27017
    type: RSPrimary
    avg_rtt_ms: 50  # Too far.
    lastUpdateTime: 0
    maxWireVersion: 5
    lastWrite: {lastWriteDate: {$numberLong: "1"}}
  - &2
    address: b:27017
    type: RSSecondary
    avg_rtt_ms: 5
    lastUpdateTime: 0
    maxWireVersion: 5
    lastWrite: {lastWriteDate: {$numberLong: "1"}}
read_preference:
  mode: Nearest
  maxStalenessMS: 2000  # 2 seconds, permitted.
suitable_servers:
- *1
- *2
in_latency_window:
- *2