Network Tool Guides

How the internet's distributed directory resolves names to addresses. Record types, TTL, DNSSEC, propagation, and reading query output.

ICMP Echo Request and Reply over IPv4. RTT, packet loss, jitter, and what each metric tells you about a path's health.

ICMPv6 Echo over IPv6. Dual-stack connectivity, Hop Limit, why ICMPv6 is mandatory, and diagnosing IPv4/IPv6 discrepancies.

TTL-based hop discovery: mapping the path from source to destination, reading RTT per hop, ECMP, MPLS tunnels, and wildcard hops.

Full HTTP request analysis: status codes, redirect chains, timing breakdown (DNS → TCP → TLS → TTFB → download), and security headers.

TLS handshake inspection: certificate chain, expiry, SANs, cipher suites, OCSP stapling, and diagnosing browser certificate errors.

TCP three-way handshake at the transport layer: open vs closed vs filtered states, common ports, firewall diagnosis, and security exposure.

How GeoIP databases estimate an IP's country, city, and ISP from registry data, latency measurements, and ISP geofeeds — and why they're approximate.

IP and domain registration data from the five Regional Internet Registries via WHOIS and its modern JSON replacement RDAP.

Autonomous System numbers, BGP routing, prefix announcements, RPKI validation, and identifying the network operator behind any IP.

OUI vendor identification from the IEEE registry: how MAC addresses are structured, locally administered addresses, and MAC randomisation.