The best textbook I know on network programming is "TCP/IP Illustrated" by Stevens.
The best textbook I know on network programming for interactive, real-time systems such as games is "Networked Virtual Environments" by Singhal et al.
Note that those are both college-level textbooks -- there aren't really any high quality networking "tutorial" books like the "for Dummies" series, because the problem itself is actually pretty complex. Kind of how there's no "rocket science for dummies" or "brain surgery for dummies" :-)
Actually I'm planning to apply a job as a game programmer in MMO game development company but the requirement listed there is "Familiarity with client/server game development techniques." I think I don't have this skill yet so I wish to learn some fundamental before going to apply for job.
So for the book that u recommended, do u think it fits my needs or is there any other books/tutorials that will suit me more?