serene% mongo --port 14920
MongoDB shell version v4.4.2
connecting to: mongodb://127.0.0.1:14920/?compressors=disabled&gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("22f6398e-eace-4944-ab13-657179ea3ac0") }
MongoDB server version: 4.9.0-alpha5
WARNING: shell and server versions do not match
---
The server generated these startup warnings when booting: 
        2021-03-04T23:58:35.361-05:00: This is a development version of MongoDB. Not recommended for production
        2021-03-04T23:58:35.361-05:00:         version: 4.9.0-alpha5
        2021-03-04T23:58:35.361-05:00: Access control is not enabled for the database. Read and write access to data and configuration is unrestricted
        2021-03-04T23:58:35.361-05:00: This server is bound to localhost. Remote systems will be unable to connect to this server. Start the server with --bind_ip <address> to specify which IP addresses it should serve responses from, or with --bind_ip_all to bind to all interfaces. If this behavior is desired, start the server with --bind_ip 127.0.0.1 to disable this warning
        2021-03-04T23:58:35.362-05:00: /sys/kernel/mm/transparent_hugepage/enabled is 'always'. We suggest setting it to 'never'
        2021-03-04T23:58:35.362-05:00: Soft rlimits for open file descriptors too low
        2021-03-04T23:58:35.362-05:00:         currentValue: 4010
        2021-03-04T23:58:35.362-05:00:         recommendedMinimum: 64000
---
MongoDB Enterprise ruby-driver-rs:PRIMARY> db.runCommand({ping:1,apiVersion:'3'})
{
	"ok" : 0,
	"errmsg" : "API version must be \"1\"",
	"code" : 322,
	"codeName" : "APIVersionError",
	"$clusterTime" : {
		"clusterTime" : Timestamp(1615066282, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	},
	"operationTime" : Timestamp(1615066282, 1)
}
MongoDB Enterprise ruby-driver-rs:PRIMARY> db.runCommand({ping:1,apiVersion:'2'})
{
	"ok" : 1,
	"$clusterTime" : {
		"clusterTime" : Timestamp(1615066282, 1),
		"signature" : {
			"hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
			"keyId" : NumberLong(0)
		}
	},
	"operationTime" : Timestamp(1615066282, 1)
}