{
"error": true,
"read_preference": {
"maxStalenessSeconds": 1,
"mode": "Nearest"
},
"topology_description": {
"servers": [
{
"address": "a:27017",
"type": "Unknown"
},
{
"address": "b:27017",
"type": "Unknown"
}
],
"type": "ReplicaSetNoPrimary"
}
}