#!/bin/sh
set -eu

usage () {
    echo "Usage: $0 HOST"
    exit 1
}

remove () {
    until [ -z "$(ssh-keygen -R "$1" 2>/dev/null)" ]
    do
        true
    done

}

if [ "$#" -ne 1 ]
then
    usage
fi

host="$1"

for i in "$host" $(dig +short "$host")
do
    remove "$i"
done
