Domain & IP Learning Center
Clear, practical guides for WHOIS, RDAP, DNS, IP networks and website diagnostics.
Each guide links to a live lookup tool, so you can check real DNS and registration data as you read.
DNS Fundamentals
8 guidesWHOIS, RDAP and DNS Explained: Registration Data vs Live Resolution
Understand which service answers domain ownership, registry and current DNS questions, and why their results can legitimately differ.
How to Troubleshoot DNS Problems: From Domain Resolution to Website Access
A practical, step-by-step workflow for finding out whether a website problem comes from DNS, HTTPS or the origin server.
Why a Website Cannot Be Reached: A Complete DNS, IP, HTTPS, and Server Checklist
A systematic way to diagnose a website that times out, shows an error page or opens only for some visitors.
What Is DNS?
A practical introduction to the system that connects domain names to internet services.
WHOIS vs RDAP vs DNS: What Is the Difference?
Learn what each lookup answers: registration data, structured registry data and live DNS resolution.
IPv4 vs IPv6: What Is the Difference?
Learn why both address families exist and how they appear in DNS.
IPv4 and IPv6 Dual-Stack Troubleshooting: Why Some Visitors Cannot Open a Website
Find out why a site works over IPv4 but fails for IPv6 users, and how to check AAAA records, routing, firewalls, TLS and CDN settings.
What Is DNS TTL and DNS Propagation?
Why DNS changes can appear at different times for different users.
IP & Networks
1 guidesDNS Record Types
8 guidesDNS Record Types Explained: A, AAAA, CNAME, MX, TXT, NS and CAA in Practice
A practical reference for the DNS records used by websites, email, verification, delegation and certificate issuance.
DNS TTL and Propagation Explained: When Do DNS Changes Take Effect?
Understand recursive caching, negative answers, resolver differences and a safe TTL workflow for DNS changes and migrations.
DNS Record Types Explained: A, AAAA, CNAME, MX, TXT, NS & CAA
A practical guide to the DNS records most often used for websites, email and verification.
A and AAAA Records Explained
See how a hostname points to IPv4 and IPv6 addresses.
CNAME Records Explained
Understand hostname aliases, resolution chains and common configuration rules.
Nameservers and NS Records
Understand DNS delegation and why authoritative name servers matter.
SOA Records Explained
Understand the zone metadata that controls serials, refresh intervals and negative caching.
SRV Records Explained
Learn how DNS can advertise the host and port for a service.
Email & Deliverability
4 guidesSPF, DKIM and DMARC Explained: How to Troubleshoot Email Delivery
Learn how three DNS-based email authentication mechanisms work together and how to investigate messages that fail authentication or land in spam.
MX Records and Email Routing
Learn how inbound email finds the mail servers for a domain.
SPF, DKIM and DMARC Explained
Understand the DNS records that help protect a domain from email spoofing.
What Is Reverse DNS (PTR)?
How PTR records map IP addresses to hostnames and why mail systems use them.
Migration & Operations
1 guidesDomains & Infrastructure
2 guidesDNS Security
2 guidesWebsite Diagnostics
5 guidesHTTP 502, 503, and 504 Errors Explained: How to Find the Upstream Failure
Understand what common 5xx responses mean and how to trace a failure through a proxy, web server and application.
Why a Website Cannot Be Reached: A Complete DNS, IP, HTTPS, and Server Checklist
A systematic way to diagnose a website that times out, shows an error page or opens only for some visitors.
HTTPS Certificate and Redirect Troubleshooting: From TLS Errors to Redirect Loops
Learn how to diagnose certificate mismatches, SNI and HTTP-to-HTTPS redirects across root domains, www hostnames, proxies and origin servers.
HTTP Status Codes and Redirect Chains
A quick guide to diagnosing availability, redirects and server responses.
How to Diagnose HTTP Redirects
Trace redirect behavior before it affects users, search visibility, or application flows.