Two parts to this:
Before whitelisting a domain or an IP range, it is worth taking some time to do some research to make sure it is safe to do so. Below I have collected a bunch of links that are good places to go to 'test' the quality of a domain and/or IP range:
- http://hosts-file.net/
- http://www.robtex.com/
- http://www.bfk.de/bfk_dnslogger.html
- http://www.google.com/safebrowsing/diagnostic?site=EXAMPLE.COM
- http://www.siteadvisor.com/sites/
- http://www.mywot.com/
- http://safeweb.norton.com/
- http://www.trustedsource.org/query/111.111.111.111
- http://www.projecthoneypot.org/
- http://malwaredomains.com/
- http://malwaredomainlist.com/
- http://www.virustotal.com/