Guides
Guides on IP addresses, VPN, network security, DNS and online privacy: step-by-step tutorials, reference tables and honest comparisons — free, no signup required.
Common Network Ports: TCP and UDP Reference List
Reference list of the most important TCP and UDP ports with service, protocol, encryption status and security notes. Quick lookup for sysadmins.
DNS Record Types — A, AAAA, CNAME, MX, TXT, SRV
All major DNS record types explained: A, AAAA, CNAME, MX, TXT, NS, SOA, SRV, CAA, PTR, DNSKEY, DS – with examples, TTL recommendations and common use cases.
Find Your Router's IP — Windows, Mac, Android, iOS
Find your router's IP address on any device: Windows, Mac, Android, iPhone, Linux. Includes default IPs for the most common router brands.
IPv4 vs IPv6 — What's the Difference?
IPv4 vs IPv6 head to head: address space, format, NAT, header, performance, security, adoption. Should I enable or disable IPv6?
Public vs Private IP — The Difference Explained
Public vs private IP addresses: differences, examples, RFC 1918 ranges, NAT, when each one matters – and how it affects self-hosting, VPN and gaming.
Static or Dynamic IP — Pros and Cons
Static vs dynamic IP explained: When do you need which? Pros, cons, costs, impact on privacy, server hosting, gaming and smart-home setups.
Subnet Mask Cheat Sheet — CIDR /8 to /32 Reference
Complete CIDR reference from /8 to /32 with subnet mask, usable hosts, wildcard mask and common deployment scenarios. Quick lookup for network engineers.
Who Can See My IP Address? Risks and Protection
Who can see your IP: websites, ISP, authorities, ad networks, chat partners. What they can derive from it – and how to protect your privacy.
Why Does My IP Address Change? Causes & Fix
Why your IP address changes: DHCP lease, ISP reconnect, router reboot, VPN, mobile networks. What it means for servers, banking and services – and how to prevent it.
How to Check SPF, DKIM and DMARC in 5 Minutes
How do I check SPF, DKIM and DMARC for a domain? Step-by-step guide with concrete commands and example records. Includes typical mistakes and how to fix them.
How to Find the IP Address of a Domain — Step-by-Step
How do I find the IP address of a domain? Direct path via DNS lookup plus host and location lookup. Includes dig/nslookup commands and why some domains return multiple IPs.
Free IP API Comparison 2026 — ipify, ipinfo & More
Honest comparison of the 6 most-used free IP address APIs in 2026. Rate limits, data fields, CORS, IPv6, pricing — with code samples and use-case recommendations.
HTTP Security Headers — Best Practices + Examples
Which HTTP headers should be set? Practical guide to CSP, HSTS, X-Frame-Options & co. with nginx and Apache examples plus a checklist for a header audit.
NordVPN vs Surfshark 2026 — Honest Comparison
NordVPN or Surfshark? Direct 2026 comparison: pricing, servers, speed, security, streaming. Which VPN fits which use case?
Remove Your IP from a Blacklist — Step-by-Step
Is your IP address on a spam blacklist? Learn how to check the status and remove your IP from DNSBLs like Spamhaus, Barracuda and SORBS. Complete walkthrough.
Ports and Firewalls — Understanding Network Security
What are ports, how do firewalls work, and why should you know which ports are open? A practical guide to network security.
IPv6 Explained – The Future of Internet Addressing
IPv6 is the successor to IPv4, offering a virtually unlimited address space. Learn how IPv6 works, how it differs from IPv4, and why the transition matters.
Port Scanner Guide — Open Ports, Services, Firewall
Open ports on your IP address reveal which services are accessible from the internet. Learn what ports are, which are dangerous, and how to scan them.
SSL Certificates Explained — HTTPS & TLS Basics
SSL/TLS certificates secure the connection between your browser and websites. Learn how HTTPS works, what certificates contain, and how to check them.
How to Change Your IP — Windows, Mac, Android, iOS
Learn how to change your IP address on Windows, macOS, Android and iOS. Switch your public or private IP with or without a VPN – step-by-step guide.
DNS Explained – The Internet's Phone Book
DNS translates domain names like google.com into IP addresses. Learn how the Domain Name System works and why DNS leaks are a privacy concern.
Subnet Calculation — CIDR, Netmask, Host Range
Learn how to calculate IP subnets: CIDR notation, netmask, broadcast address and host range explained step by step with practical examples.
What Is a VPN? The Ultimate Beginner's Guide
A VPN protects your privacy online by encrypting your connection and hiding your IP address. Learn how VPNs work and when you should use one.
What Is an IP Address? Simply Explained
An IP address is your unique identifier on the internet. Learn what IP addresses are, how they work, and why they matter for your privacy.