MongoDB Replication Set Configuration Issue on CentOS 7 My mongodb instance will not run as standalone and I haven't been able to discover why.  Its probably something simple.  Please point me in the right direction.

Linux myserver 3.10.0-514.el7.x86_64 #1 SMP Tue Nov 22 16:42:41 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux

 mongo -version
MongoDB shell version v4.0.6


running the command:


  
    mongo --host 10.0.0.7/admin --port 27017 -u user -p mypassword
  


returns:

MongoDB shell version v3.4.13
connecting to: mongodb://admin:27017/?replicaSet=10.0.0.7
2019-03-06T00:54:32.412-0500 I NETWORK  [thread1] Starting new replica set monitor for 10.0.0.7/admin:27017
2019-03-06T00:54:32.414-0500 I NETWORK  [thread1] getaddrinfo("admin") failed: Name or service not known
2019-03-06T00:54:32.414-0500 W NETWORK  [thread1] No primary detected for set 10.0.0.7
2019-03-06T00:54:32.414-0500 I NETWORK  [thread1] All nodes for set 10.0.0.7 are down. This has happened for 1 checks in a row.
2019-03-06T00:54:32.914-0500 I NETWORK  [thread1] getaddrinfo("admin") failed: Name or service not known


So I logged into mongo shell on the host and ran:

use admin
 show users

{
        "_id" : "admin.myname",
        "user" : "myname",
        "db" : "admin",
        "roles" : [
                {
                        "role" : "readWriteAnyDatabase",
                        "db" : "admin"
                },
                {
                        "role" : "root",
                        "db" : "admin"
                },
                {
                        "role" : "userAdminAnyDatabase",
                        "db" : "admin"
                }
        ],
        "mechanisms" : [
                "SCRAM-SHA-1",
                "SCRAM-SHA-256"
        ] }


and


  rs.status()


{
        "ok" : 0,
        "errmsg" : "not running with --replSet",
        "code" : 76,
        "codeName" : "NoReplicationEnabled"
}


Mongd.conf

# mongod.conf

# for documentation of all options, see:
#   http://docs.mongodb.org/manual/reference/configuration-options/

# where to write logging data.
systemLog:
  destination: file
  logAppend: true
  path: /var/log/mongodb/mongod.log

# Where and how to store data.
storage:
#  dbPath: /var/lib/mongo
  dbPath: /data/mongo
  journal:
    enabled: true
#  engine:
#  mmapv1:
#  wiredTiger:

# how the process runs
processManagement:
  fork: true  # fork and run in background
  pidFilePath: /var/run/mongodb/mongod.pid  # location of pidfile
  timeZoneInfo: /usr/share/zoneinfo

# network interfaces
net:
  port: 27017
#  bindIp: 127.0.0.1  # Enter 0.0.0.0,:: to bind to all IPv4 and IPv6 addresses or, alternatively, use the net.bindIpAll setting.
  bindIpAll: true

security:
  authorization: "enabled"

#operationProfiling:

#replication:

#sharding:

## Enterprise-Only Options

#auditLog:

#snmp:
mongo --host 10.0.0.7/admin --port 27017 -u user -p mypassword


The above command takes 10.0.0.7 as replica set name and admin as the hostname. That is the reason you are getting the error.

Use any of the following commands to connect to your MongoDB database

mongo 10.0.0.7/admin --port 27017 -u user -p mypassword

mongo admin --host 10.0.0.7 --port 27017 -u user -p mypassword