Massive amount of blocked transactions in Ironport

[DWalker79]

Over the past 90 days, I have 50.0M attempts and blocks heading to fastcast.go.com (resolves to fastcast.gns.go.com 199.181.132.89).  Has anyone dealt with this particular url in their reports?  If they have, what steps should I take next?  I can't seem to find any good information out there concerning this, and I'm in the process of digging through the worst offender users/machines to see what I can find.

[Handy Putra]

From the look of it the traffic comes from an application for fastcast that doing mobile video news (http://wemedia.com/2011/03/28/introducing-fast-cast/).

This particular might have automatic traffic going out to the internet.

To confirm further, check the accesslogs from the appliance to see the source IP address(client) for those traffic and once found check the machine to see any apps in that machine that causing this.

[DWalker79]

The users with the most attempts are also some of my heaviest browsers.  My guess is that they are leaving web pages open for long periods of time, resulting in an inordinate number of transactions, in the half million per day range.

I've also found the name and IP seem to belong to Disney, and is mostly related to ESPN sites.

Thank you so much for your quick response.