> How Domain Name Systems (DNS) work.

> Registering and using domains.

> Understanding TCP/IP.

> Basic network debugging. (ex. why aren't I able to to connect to my new website? Hint: The port isn't open)

> Understanding what a VPN is.

> The anatomy of an HTTP transaction.

> The HTTP request verbs and when the use them.

> Recognize the main response codes and when to use which ones.

> What a stateless protocol is and why it matters.

> Recognize popular headers and how to add your own.

> Working with HTTP outside the browser. (REST clients, curl, etc)

> SSL, what it is, how it works, and why you should use it.

> Remote access using SSH.

> Basic shell commands (cd, ls, cp, mv, mkdir, ...).

> Learn how to use grep.

> Get familiar with a command line text editor (vim, Emacs, nano, ...).

> Understand file permissions and how to change them.

> Learn what environment variables are and how/when to use them.

> Learn how to use .bashrc

> Learn how to use a package manager (apt, yum, ...)

> Learn to find and read logs for your services.

> Learn to manage services (start, stop, restart, ...)

> Learn basic bash scripting.

> Learn the basic commands (init, add, commit, status, checkout, ...)

> Learn to configure remote repositories.

> Learn to use fetch, pull, push.

> Learn to work with branches. (create, merge, ...)

> Learn what rebase is and how to use it.

> Learn how to resolve conflicts.

> Learn how to use stash.

> Learn to use the console to find errors and debug your code.

> Learn to use the inspection tool to view/change your markup and CSS in the browser.

> Learn how to debug Javascript (call stack, breakpoints, object inspection, ...)

> Learn to inspect and debug HTTP transactions.

> Learn to profile websites to identify performance issues.