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IP and request guides

Short explanations for common IP, network, browser, and HTTP request terms.

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A plain-English guide to IP addresses, public IPs, IPv4, IPv6, and what websites can infer from an address.

Learn what a public IP address can reveal, what it cannot prove, and why IP geolocation should be treated as approximate.

Learn the difference between public IP addresses, private local addresses, NAT, and why websites usually see your router or VPN.

Find the private local IP address on Windows, macOS, Linux, iPhone, Android, and router admin screens.

Understand the practical difference between IPv4 and IPv6 addresses, address length, notation, and network ranges.

Learn what CIDR notation means, how prefix lengths work, and how CIDR ranges apply to IPv4 and IPv6 networks.

A quick reference for common IPv4 and IPv6 CIDR prefix lengths, address counts, and when to use each range.

Understand Autonomous System Numbers, network owners, routing context, and why ASN data appears in IP lookup tools.

Understand common DNS record types such as A, AAAA, CNAME, MX, NS, TXT, and PTR, and when to look each one up.

Learn how reverse DNS maps IP addresses to PTR hostnames, why PTR records matter, and why missing reverse DNS is common.

Learn what a user-agent string is, what browser and bot signals it can contain, and why it should not be treated as proof.

Understand HTTP request headers, common fields, proxy headers, sensitive headers, and what ShowIP exposes safely.