title: DFP returning empty vast files (ads)
body: <p>I am using DFP to serve ads, and fiddler to monitor the requests.</p>
  
  <p>After 3 GET requests to the dfp server, in a short period of time (say 30 seconds), every subsequent request will a list of empty ads.</p>
  
  <p>Does DFP have some sort of spam protection? if so, is there a way around it? debugging an ad implementation is quite slow when you're ad payloads are empty!</p>