#!/bin/bash

echo $1

ssh-keygen -R $1
IP=$(getent hosts $1 |awk '{print $1}')
ssh-keygen -R $IP
# Remove the "-H" option in the two following lines if you want the hostnames
# in known_hosts to be human readable (not hashed).
ssh-keyscan -H $1 >>~/.ssh/known_hosts 2>/dev/null
ssh-keyscan -H $IP >>~/.ssh/known_hosts 2>/dev/null