The Inside AdWords announced that starting April 1, AdWords will no longer allow redirects and vanity URLs in place of ad landing pages. This is in line with Google’s move toward providing more relevant advertising results and higher quality experiences to users.
AdWords will require that URLs of advertisers’ ad displays should match their destination or landing page URL. As an example, if an advertiser’s destination URL is www.searchenginejournal.com, the display URL or the Ad’s landing page URL should be the same.
Any display URL that looks similar to www.searchenginejournal.com will not be accepted such as a link to a sub TLD, spelling variation in domain name even if the domain is live and redirects to searchenginejournal.
For advertisers who use tracking URLs, only ads which have the same display URL (regardless if its a subfolder of the main domain) as the Landing page would be acceptable even if a tracking URL is different.
So, www.searchenginejournal.com/ads as a display URL with a landing page URL, www.searchenginejournal and with tracking URL, www.trackingurl.com/ads is acceptable to AdWords. But if the landing page URL becomes www.trackingurl.com, it will not be acceptable to AdWords.
Subdomains for both landing and display ad URLs are still acceptable.