Example

How to login via SSH using Specfic SSH Private Key

Login via ssh to use specific identity '"IdentitiesOnly=yes"'
Path to Private Key : -i /home/user/.ssh/id_red_penguin
Path to Host: root@red-penguin-60185.zap.cloud  (root is user context, "red-penguin-60185.zap.cloud" vm hosted named "red-penguin-60185" on some IaaS provider called "zap.cloud"

ssh -o "IdentitiesOnly=yes" -i /home/user/.ssh/id_red_penguin root@red-penguin-60185.zap.cloud