I have a friend who has signed up to Yellow for Google Adwords. I look after his site for him and Yellow emailed me requesting that I insert the code snippets in to his pages so they can run Google Tag Manager ..... but that's another story.
Anyway, on checking his existing Analytics I saw an entry under hostnames for <<his domain>>.y9.co.nz which I see is registered to Yellow. When I go to the URL it redirects back to his site.
Any ideas why they would be doing this?