Disable SSH host key checking

I summarized this from Linux Commando: How to disable SSH host key checking

He suggested 3 approaches

1. $ sed -i 3d ~/.ssh/known_hosts
2. Use parameters
   * StrictHostKeyCheckin
   * UserKnownHostsFile
   

   ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no username@hostname

3. Config file ~/.ssh/config (or /etc/ssh/ssh_config for global) & restart ssh
   

   Host 192.168.0.*
   StrictHostKeyChecking no
   UserKnownHostsFile=/dev/null