• CNAME or A/AAA redirect to unspammer
• CA with on-demand certificate vending
• Send empty VAST/VMAP responses to block advertisements

When the ad server does not or cannot return an Ad, the VAST response should contain only the root <VAST> element with optional <Error> element, as shown below:

<VAST version="4.1">
    <Error>
        <![CDATA[http://adserver.com/noad.gif]]>
    </Error>
</VAST>

The VAST <Error> element is optional but if included, the media player must send a request to the URI provided when the VAST response returns an empty InLine response after a chain of one or more wrappers. If an [ERRORCODE] macro is included, the media player should substitute with error code 303.

Besides the VAST level <Error> resource file, no other tracking resource requests are required of the media player in a no-ad response in either the Inline Ad or any Wrappers.

var googlebotHeaders = map[string]string{
	"User-Agent": "Mozilla/5.0 (Linux; Android 6.0.1; Nexus 5X Build/MMB29P) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/W.X.Y.Z Mobile Safari/537.36 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)",
}