DTrace landed in FreeBSD 7.1 in 2009. DTrace is an observability framework that enables dynamic tracing of programs, and the FreeBSD Kernel. It offers an incredible view into the operation of programs, and is an excellent tool for debugging and performing analysis of complex software. Using the full power of FDT probes requires familiar knowledge with how things are implemented. SDT probes and specific providers like ip, tcp and udp offer insights into the internal behavior of the kernel without requiring a high level of knowledge of the underlying code.