## Reducing SSH Login Delay
Setting `UseDNS no` in the VM's `/etc/ssh/sshd_config` or `/etc/sshd_config` has made it much faster to ssh into VMs.

centos@128.31.24.158 is a m1.small VM in Kaizen with a public IP.

With `UseDNS yes` (the default in Ubuntu 16.04), `ssh -A centos@128.31.24.158 'exit'` 
(ssh into the VM and then immediately exit) takes **5.8 seconds**.

With `UseDNS no`, `ssh -A centos@128.31.24.158 'exit'` takes **248 ms**. 
So changing this option shaves 5.5 seconds off the time it takes me to ssh into a VM.

More info about the UseDNS option to see if you actually need it enabled:
 -  [What's the point of usedns option?](http://unix.stackexchange.com/questions/56941/what-is-the-point-of-sshd-usedns-option)
 -  [OpenSSH Bug Report](https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/424371)

To configure:
 1. `sudo vim /etc/ssh/sshd_config` or `sudo vim /etc/sshd_config`
 1. Change `UseDNS yes` to `UseDNS no` or add `UseDNS no` to the file, then quit vim
 1. Restart ssh `sudo service sshd restart`