Systems and Methods of DNS Grey Listing

To circumvent being blacklisted by an ISP, some viruses use a domain name generator algorithm or a domain generator algorithm (DGA). In an example, the DGA may use the current date and time to generate a random domain name based on the date. So for a given date, the botnet registers a particular domain in order to control the Trojan horse virus. The domain name that the botnet uses typically changes every day, which helps circumvent blacklisting. To counteract that, the disclosed systems and methods of DNS greylisting place a domain name in a grey list for a time period, for example a day, that the domain is resolved by the ISP. The first time the ISP experiences a customer trying to contact a particular domain, the ISP prevents the domain from resolving. After the time period (for example, 24 hours) expires, the domain is allowed to resolve normally.