Only if you plan on becoming a low-level TCP/IP implementation engineer or some other such niche field in the very immediate future. The vast majority of worki

Only if you plan on becoming a low-level TCP/IP implementation engineer or some other such niche field in the very immediate future. The vast majority of working programmers can be extremely effective without knowing much more than basic socket usage and perhaps the basics of how NAT setups can work against you if you're doing something other than just pure web-browser networking. Having said that, knowing how in-the-wild network protocols work in general is one of those things (like knowing how compilers work) that can broaden your horizons and are probably worth learning for that reason, just don't worry too much about retaining minutia about them that you can easily look up should the need arise.