Tools & Concepts
WHOIS, traceroute, ping, port numbers, HTTP status codes, and subnet cheat sheets. The practical reference stuff you'll actually bookmark.
Common Port Numbers: The Complete Reference Table
A complete reference guide to the most important TCP and UDP port numbers, from HTTP (80) to HTTPS (443), SSH (22) to …
HTTP Status Codes: Every Code Explained
The complete reference guide to HTTP status codes. 1xx informational, 2xx success, 3xx redirect, 4xx client error, 5xx …
Subnet Cheat Sheet: CIDR, Mask, Hosts at a Glance
The complete subnet reference table. Every CIDR prefix from /0 to /32 with subnet masks, total addresses, usable hosts, …
What Is Ping? The Simplest Network Diagnostic Tool
Ping tests whether a host is reachable and measures round-trip latency. Learn how ping works, how to read the output, …
What Is Traceroute? Mapping the Path Your Packets Take
Traceroute shows every router hop between you and a destination, revealing the network path, latency at each step, and …
What Is WHOIS? The Internet's Public Records System
WHOIS is a protocol for querying databases that store information about domain name registrations and IP address …