There are many techniques for locking down your applications to prevent unwelcomed visitors. It is always important to implement layered security controls using as many techniques as you can. One method of locking down a site is to whitelist who can access it.
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He is a solution consultant focused on helping organization build high quality application effectively utilizing DevOps practices. He is a Microsoft DevOps / ALM Ranger and you can reach him on Twitter at @mikedouglasdev