This book is for IT professionals working hard to keep up with new technology whilst retaining old skills learnt. Extremely useful as an office or interview preparation reference, it is a condensed deep dive and refresher into BGP, EIGRP, IS-IS and OSPF routing giving detailed information in a format easy to remember. There are mnemonics and codes to assist with fast recall of information and topics are laid out in a way to ensure fast retention of technical aspects. It covers the protocol backgrounds, metrics and their order of preference, attributes and routing scenarios amongst other items for BGP, EIGRP, IS-IS and OSPF. Furthermore it is very quick to read and avoids any necessary explanations focusing exactly on what you need to know.