Typically, DDoS refers to DDoS 'attacks'. DDoS is short for Distributed Denial of Service. Ok, so what's that?!? It's a type of malicious attack where extremely large quantities of connections (typically from multiple infected systems) are made to a targeted victim (or server). This is in an effort to make an online service (website/server) unavailable by overwhelming it with traffic.
See more via WikiPedia - DDoS.
KnownHost offers DDoS protection for all services. For more details on this protection please visit KnownHost DDoS Protection. Please read our How to prevent DDoS attacks article for some tips and information regarding additional DDoS prevention.
If you've become victim of a DDoS attack, very few actions can be taken during the attack. Please open a Support Ticket for assistance.