So every now and then, I will notice that our OpenDNS service will not be blocking queries. I usually perform the following steps to resolve.
Login to each DNS server and “Clear DNS Cache”, then wait 5 minutes.
Pull up a command prompt and type:
ping 220.127.116.11 nslookup whoami.akamai.net. netsh interface ip show dns nslookup -type=txt debug.opendns.com
Go to test blocked site: https://phish.opendns.com/main?url=www.internetbadguys.com&server=dfw2&prefs=&tagging=&nref