Template:FAQ:Agent 09
Most of the MIB information supplied by the Net-SNMP agent is provided by C-coded implementation modules, and the choice of which modules to include is usually made when the agent is first built. Adding new MIB modules would therefore require re-compiling the agent. This is not always convenient - particularly when working with a production system, and/or pre-installed binaries.
Dynamically loaded modules are a means of including a MIB implementation module within the main SNMP agent (or an AgentX subagent) without needing to re-compile and re-link the agent binary. Instead, details of the module(s) to load are specified in the configuration file, and the agent locates the files listed, and merges them in at run time.
See http://www.net-snmp.org/tutorial-5/toolkit/dlmod/ for more information.