title: How to detect a unique visitor is unique?
body: <p>I am in the early stages of coming up with a web application that asks the user to vote on something and then see the results on a map.  There will be well over 100 options to choose from (suburbs).  </p>
  
  <p>I understand how I could make use of cookies to come up with some code along the lines of:</p>
  
  <p><em>If not unique visitor Then dont show them Voting Screen, take them straight to map showing results.</em></p>
  
  <p>However, this is still subject to manipulation by anyone who understands that deleting their cookies will give them a new vote.</p>
  
  <p>My application does have a backend SQL Server, so I was thinking that perhaps i could persist their IP address, but then cross comparing this on every initialise from a visitor sounds like it might cause delays.</p>
  
  <p>The application will be public domain and I want to avoid any sort of login to the application, so that I can gather as many votes as possible.</p>
  
  <p><strong>What techniques or plugins might be able to assist me in preventing a user from keep voting for a particular answer multiple times?</strong> </p>