DomScan

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Guides, product updates, domain research, DNS explainers, and technical breakdowns from DomScan.

July 23, 2026 Esteve Castells 12 min

WHOIS API in 2026: DomScan endpoints, RDAP sources, and safe integration

DomScan's WHOIS API is RDAP-first, with traditional WHOIS and DNS fallbacks where coverage requires them. This guide documents the live endpoints, response sources, cache behavior, costs, privacy limits, and error handling.

WHOISRDAPAPIDomain IntelligenceAutomation
July 16, 2026 Esteve Castells 12 min

WHOIS Privacy in 2026: Redaction, Proxy Services, and Disclosure

ICANN's current policy separates public from nonpublic registration data. This guide explains redaction, privacy and proxy services, RDRS, RDAP, and the limits of domain lookups.

WHOISRDAPPrivacyRegistration DataRDRSInvestigation
July 9, 2026 Esteve Castells 8 min

WHOIS History After the RDAP Cutover: How Domain Snapshots Work

Historical registration snapshots can show when a registrar, nameserver, status, or expiry date changed. This guide explains what those observations prove, what they do not, and how DomScan coverage works.

WHOISRDAPWHOIS HistoryDomain InvestigationBrand ProtectionDue Diligence
July 2, 2026 Esteve Castells 14 min

WHOIS domain search after the RDAP cutover: what registration data can tell you

A WHOIS domain search no longer means querying one plaintext directory for a website owner. For generic domains, RDAP is now the definitive source, and the public result usually describes registration state rather than personal identity.

WHOISRDAPDomain RegistrationRegistration DataOSINTICANN
June 25, 2026 Esteve Castells 9 min

IP WHOIS and RDAP: find the registered network holder

IP registration data identifies the network holder and operational contacts for an address range. It does not identify a cloud customer, physical server, or individual user.

WHOISIP LookupRDAPRIRNetwork IntelligenceOSINT
June 18, 2026 Esteve Castells 12 min

WHOIS and RDAP lookup: a practical guide to domain registration data

RDAP is now the definitive source for gTLD registration data, while WHOIS remains in a smaller legacy role. Learn to read dates, status codes, nameservers, DNSSEC, and privacy signals without treating them as proof of ownership.

WHOISRDAPDomain Registration DataEPP Status CodesPrivacyDomain Operations
June 11, 2026 Esteve Castells 10 min

TXT Records Explained: SPF, DKIM, DMARC and Beyond

TXT records started as a place for human-readable notes in DNS. They now carry the machine-critical data that decides whether your email arrives, your domain is verified, and your security policies are enforced.

DNSTXT RecordSPFDKIMDMARCEmail Security
June 4, 2026 Esteve Castells 13 min

A Record vs CNAME: When to Use Each DNS Record Type

A records map hostnames to IP addresses. CNAMEs alias one hostname to another. The choice between them determines how CDN routing, SSL issuance, email delivery, and DNS migrations actually behave in production.

DNSA RecordCNAMEInfrastructureNetworking
May 28, 2026 Esteve Castells 11 min

NS Record Check: How to Verify Nameserver Configuration

NS records are the delegation chain of DNS. Get them wrong and your entire domain goes dark. Here is how to check, diagnose, and fix nameserver configuration problems before they become outages.

DNSNS RecordsNameserversDomain ConfigurationInfrastructure
May 21, 2026 Esteve Castells 15 min

MX Record Lookup: How Email Routing Works

When you send an email, your mail server queries MX records to find which servers accept mail for the destination domain. This guide explains MX priority, fallback chains, common configurations, security implications, and troubleshooting.

DNSMX RecordsEmailSecurityInfrastructure
May 14, 2026 Esteve Castells 16 min

Understanding DNS Servers: Types, Setup, and Troubleshooting

DNS server means different things depending on context. This guide breaks down the four types, compares public resolvers, walks through configuration on every major OS, and covers troubleshooting and security.

DNSDNS ServerNetworkingInfrastructureSecurityTroubleshooting
May 7, 2026 Esteve Castells 13 min

DNS Leak Test: What It Is and Why It Matters for Your Privacy

A DNS leak exposes every domain you visit to your ISP, even when you think a VPN or encrypted resolver is protecting you. Learn what causes DNS leaks, how to test for them, and how to fix them permanently.

DNSPrivacySecurityVPNDNS-over-HTTPSDNS-over-TLS
April 30, 2026 Esteve Castells 11 min

IP address lookup: geolocation, ASN, privacy, and hard limits

A deeper account of what an IP address can reveal through allocation records, BGP, RPKI, geolocation, and DNS, plus the effects of anycast, NAT, VPNs, and reassignment.

IP Address LookupGeolocationASNBGPRPKIIPv4IPv6Network Privacy
April 30, 2026 Esteve Castells 12 min

DNS Checker: A Rigorous Guide to Verifying DNS Changes

A DNS result is one observation, not proof of global propagation. Learn how to check authority, delegation, caches, DNSSEC, and real client paths without overclaiming.

DNSDNS CheckerDNS VerificationDNS RecordsCachingInfrastructure
April 23, 2026 Esteve Castells 15 min

What Is a DNS Lookup and How Does It Work?

Every URL you visit starts with a DNS lookup that finishes in under 100 milliseconds. This guide walks through the full resolution chain, record types, caching, common errors, and security signals.

DNSDNS LookupInfrastructureSecurityNetworking
April 23, 2026 Esteve Castells 10 min

How to read an IP lookup without overclaiming

A practical guide to DomScan IP results: geolocation estimates, ASN context, PTR and FCrDNS, security flags, raw RDAP follow-up, and the limits of reverse IP evidence.

IP LookupGeolocationASNRDAPReverse DNSFCrDNSNetwork IntelligenceIncident Response
April 14, 2026 Esteve Castells 7 min

Bulk WHOIS Lookup: How to Research Thousands of Domains Efficiently

Bulk WHOIS work is less about sending thousands of queries than about turning inconsistent registration data into something you can actually analyse. This guide explains how to do that well.

WHOISBulk ResearchDomainsInvestigation
April 14, 2026 Esteve Castells 8 min

Domain Expiration Monitoring: How to Never Lose a Critical Domain

Domain loss is usually an ownership and process failure long before it becomes a registrar-date problem. This guide explains how to monitor critical domains so they do not quietly slide toward lapse.

DomainsExpirationMonitoringWHOIS
April 14, 2026 Esteve Castells 8 min

Domain Reputation: What It Is, Why It Matters, and How to Improve It

Domain reputation is the accumulated trust judgment attached to your domain identity. This guide explains what feeds it, how it degrades, and what operators can do to improve it without chasing myths.

ReputationDomainsEmail SecurityTrust
April 14, 2026 Esteve Castells 8 min

Attack Surface Management: A Complete Guide for Security Teams

Attack surface management is the work of turning forgotten internet-facing assets into observable, owned, and prioritised risk. This guide explains how domain-led discovery makes that possible.

SecurityASMDomainsInfrastructure
April 14, 2026 Esteve Castells 8 min

SSL Certificate Monitoring: How to Prevent Costly Expiry Outages

Certificate monitoring should cover trust drift, deployment mistakes, and unexpected issuance, not merely one date on a calendar. This guide explains how to build a monitoring routine that prevents outages.

SSLTLSMonitoringCertificates
April 14, 2026 Esteve Castells 7 min

What Is an SSL Certificate Chain? How Certificate Trust Works

Browsers trust chains, not isolated leaf certificates. This guide explains roots, intermediates, and why certificate trust fails in production even when a certificate looks “valid.”

SSLTLSCertificatesHTTPSSecurity
April 14, 2026 Esteve Castells 8 min

How Long Does DNS Propagation Take? The Technical Reality

DNS propagation is not one global timer. It is the practical effect of caches, TTLs, resolver behaviour, and where the change was made. This guide explains what actually determines visibility after a DNS update.

DNSPropagationTTLInfrastructure
April 14, 2026 Esteve Castells 8 min

DNS Record Types Explained: A, AAAA, CNAME, MX, TXT, and Beyond

DNS records are easy to define and much harder to operate well together. This guide explains the major record types, what question each one answers, and where teams create avoidable confusion.

DNSA RecordMXTXTInfrastructure
April 14, 2026 Esteve Castells 8 min

How to Read and Analyze DMARC Reports: A Practical Guide

DMARC reports are useful only when they become operational decisions. This guide explains what aggregate reports actually show, how to triage them, and how to use them for policy rollout.

DMARCEmail SecurityReportingDeliverability