Well, I was following this tutorial (https://www.digitalocean.com/community/articles/how-to-create-vanity-or-branded-nameservers-with-digitalocean-cloud-servers) and saw that there're only tutorials for installing BIND DNS Server on CentOS not in Ubuntu. I've created two new Droplets name ns1.lalande.com.br and ns2.lalande.com.br as tutorial asked, with ubuntu 14.04 X64. In both I will install BIND. There's is a problem using CentOS for my DNS Servers and Ubuntu to host? I guess not... but I'm insecure with my server skills.. :'(