This script cycles IP addresses of a domain name registered with now-dns.com (Ubuntu and Centos)

ChangeIP-Now-DNS.sh

#!/bin/bash
USERNAME="Now dns username"
PASSWORD="Now dns password"
HOSTNAME="testsite.now-dns.net" #Your domain
IP=()
#Create a file named ip.txt and add all of your IP addresses in it separated by new line
input="ip.txt"
while IFS= read -r var
do
  IP+=("$var")
done < "$input"
while true; do
    for i in "${IP[@]}"
    do
        echo "Changing IP to $i"
        curl -u "$USERNAME":"$PASSWORD" "https://now-dns.com/update?hostname=$HOSTNAME&myip=$i"
		#Change delay between changing IPs if you want
        sleep 3600
    done
	IP=()
	while IFS= read -r var
	do
  		IP+=("$var")
	done < "$input"
done
#Run script as service or with tmux or screen; CTRL-C to terminate

New version supports changing IP's while the script is running. Just change IP addresses in ip.txt