you can monitor the status of that site using the Google Safe Browsing diagnostics page for that site
http://www.google.com/safebrowsing/diagnostic?site=ads.dentsu360.com/banner/adshow.php
please surf the above url
you will see the following results
Safe Browsing
Diagnostic page for ads.dentsu360.com
What is the current listing status for ads.dentsu360.com?
This site is not currently listed as suspicious.
What happened when Google visited this site?
Google has not visited this site within the past 90 days.
Has this site acted as an intermediary resulting in further distribution of malware?
Over the past 90 days, ads.dentsu360.com did not appear to function as an intermediary for the infection of any sites.
Has this site hosted malware?
No, this site has not hosted malicious software over the past 90 days.
Next steps:
• Return to the previous page.
• If you are the owner of this web site, you can request a review of your site using Google Webmaster Tools. More information about the review process is available in Google's Webmaster Help Center.