Ping of Sharded Cluster

I am currently studying several DBs together.
While studying Redis’ Cluster, I suddenly became curious about MongoDB’s Sharded Cluster.

In the Redis Cluster, all nodes (Master, Replica) exchange ping with each other as shown below.

How do MongoDB Sharded Cluster exchange ping with each components?

First of all, I know that Replica Set exchanges heartbeats with each other.
And I guess Config Server and Shards, Config Server and mongos will ping each other.

  1. I wonder if all components exchange ping with each other.

  2. And if you send and receive, I also wonder if the components send and receive ping for each of the Replica Set members.