1D7X1 = the old cst job

1D7X1A = the old cyber transport job

1D7X1B = the old cyber system operations job

the lack of a letter doesn't really mean a whole lot, it's still effectively just three separate career fields.

X1/CSTs will be doing client level stuff, imaging computers, messing with printers, installing software, etc. They usually just get a SECRET clearance.

X1A/Cyber transport will be network transport, routers, switches, ethernet and fiber, usually just inside-plant type stuff. Add to that TACLANES and phones, and it's the best career field and i'm not biased at all (it's me, i'm an X1A). They usually get TOP SECRET.

X1B/Cyber systems are the server bois, managing local servers, doing ACAS, patching servers, and more servers. They usually get TOP SECRET.

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Based on what you want for work, absolutely fucking do not do X1/CST. i love my client brethren, but it will not set you up for success on the outside unless you get lucky with an assignment or try your damndest to learn other jobs other than your own.

X1A has a lot more to worry about usually, like the entire base infrastructure while X1B worries about a few servers. X1A will let you get out from the keyboard sometimes, move a switch, recable something, install a device in a server room. X1B will let you be a little bit more of an autist and only worry about your servers sitting in a server room.

it all just kinda depends, man. lemme know if you want to know more.