I'm generally not a pro-cert guy but this is why I believe in the vendor-agnostic comptia network+ cert. I have state college BS in CIS and I have a MS in CS, worked in helpdesk, sysadmin, IT manager, and now onto db dev stuff, but when I review the checklist for comptia network+, it's everything they briefly touched on in college plus a lot more. Without major commitment, I honestly don't think I'd pass if I took the test. I feel like I only know about 40% of it. I'd think that if every helpdesk candidate had net+ mastery, and not just brain-dumped the test, helpdesk departments wouldn't struggle so much with talent and retainage.
While I've never considered myself a network guy, I firmly believe that anything past simple level 1 helpdesk pc/application/phone support should know the foundations of data and computer communications. Right now I'm doing database development. But it touches other things. Automation, bash, ssh, telnet, ftp, sftp, tls, dns, rsa keys, host files, and more. I'd be embarrassed to think about applying for a helpdesk infrastructure role without knowing these protocols and technologies.