From Seo Wiki - Search Engine Optimization and Programming Languages
DynRBL stands for "Dynamic Realtime Black List". Dynamic nature of information coming from dynamic nature of sources. For example, it can be production mail systems with integrated sensors.
Idea under dynamic RBL database is to describe malicious types of activity in covered address space. Dynamic nature solves the problem of constantly changing environment, as it exists in Internet. The power of a dynamic approach in precision and propagation speed. While precision depends on quality of algorithms, higher propagation speed can be reached by using DNSBL-style database.