Reader's review:
Summary: sweeping and up to date view
For the electronic engineer or computer scientist, Halsall provides a detailed and sweeping view of current computer networks. With an understandable emphasis on the Internet. To those readers who might consider computer networking synonymous with the Internet, the first few chapters explain otherwise. Like the telephone networks. Originally all analog, they are now mostly digital. Halsall goes through the sundry alphabet soup of ISDN, ADSL, SONET and the like. He shows that one of their defining characteristics is a circuit switching approach, which gives a very high reliability.
The book also covers recent developments in wireless nets. Including the infrared Bluetooth and the cellphone nets. Where the latter arguably affects as many people as the Internet.
Finally, as he ascends the protocol stack (which is another concept clearly explained), he gets to the Internet. Detailed exposition of DNS, which is one of the core functionalities. Email is also gone into, as this was the first killer app of the Internet. As someone who is involved with antispam technology, I found his description of the email structure and relaying to be concise and spot on. A good level of explanation that covers all the key points.
Naturally, for all of the book's topics, you can find entire books devoted to each. But the encapsulated view of the book is hard to beat.