In my field it is Computer Networking: A Top-down Approach by Kurose. I've been using it as the main textbook for computer networking course for more than ten years.
On related notes, for the past few weeks I've spent countless hours searching and compiling good to excellent textbooks in the field of engineering and computer science. Perhaps I can share the information in the near future.
Look into teachyourselfcs.com. They have a good list of areas every good programmer should be comfortable with and a recommendation for books/lectures that teaches that well. They explain why each area is important to learn and why the book is an apt choice.
They recommend Kurose and Ross for networking too, though I disagree. I feel like High Performance Browser Networking (free at hpbn.co) is superior.
On related notes, for the past few weeks I've spent countless hours searching and compiling good to excellent textbooks in the field of engineering and computer science. Perhaps I can share the information in the near future.