Networking, Web, and APIs

How systems talk to each other: networks, HTTP, JSON and TLS.

0% of topics familiar or confident

Checklist: 0 of 6 items

Topics

Networking BasicsExpected level: Working
Understand IP addresses, DNS, ports, localhost, and firewalls.
Not reviewed
HTTP FundamentalsExpected level: Working
Learn requests, responses, methods, status codes, and headers, and inspect them with developer tools.
Not reviewed
JSON FundamentalsExpected level: Proficient
Read and create common API payloads.
Not reviewed
API Testing ToolsExpected level: Working
Use tools to inspect and test integrations.
Not reviewed
TLS and HTTPS BasicsExpected level: Awareness
Understand certificates, encryption in transit, and typical certificate errors.
Not reviewed

You should be able to do each of these without help.

Explain what DNS, an IP address, and a port are. Describe how they work together when you open a site or start a local server.Related: Networking Basics
Call an API and interpret the status code, headers, and JSON body. Use a tool such as curl or Postman, and say whether the call worked and how you know.Related: HTTP Fundamentals, JSON Fundamentals, API Testing Tools
Explain the difference between 401, 403, 404, and 500. For each one, say whether the fault is likely with the caller or the server and what you would check first.Related: HTTP Fundamentals
Describe what HTTPS adds when a client calls an API. Explain what the certificate and the encrypted connection protect, and recognise a certificate error such as an expired or mismatched certificate.Related: TLS and HTTPS Basics, HTTP Fundamentals, Networking Basics
Work out whether a failed connection is a name lookup problem, a closed port or a firewall. Use commands such as dig or Resolve-DnsName and nc or Test-NetConnection, and read what each result tells you.Related: Networking Basics
Fix an invalid JSON payload by hand. Spot a trailing comma, single quotes or a missing bracket, and say what each parse error means.Related: JSON Fundamentals