{
"heartbeatFrequencyMS": 10000,
"in_latency_window": [],
"read_preference": {
"maxStalenessSeconds": 1,
"mode": "Nearest"
},
"suitable_servers": [],
"topology_description": {
"servers": [
{
"address": "a:27017",
"type": "Unknown"
}
],
"type": "Unknown"
}
}