# NsLookup.io

> NsLookup.io is a DNS lookup, email authentication, and network diagnostics platform that helps IT professionals, cybersecurity teams, developers, system administrators, and domain owners troubleshoot DNS issues, verify email authentication records, monitor website infrastructure, and improve domain security. The platform provides free tools for DNS lookups, SSL analysis, DNS health monitoring, security scanning, website insights, and educational resources covering DNS, email authentication, and internet infrastructure.

## DNS Lookup Tools

- [DNS Lookup](https://www.nslookup.io/): Query DNS records for any domain and inspect DNS configuration.
- [A Record Lookup](https://www.nslookup.io/a-lookup/): Retrieve IPv4 (A) records for a domain.
- [AAAA Record Lookup](https://www.nslookup.io/aaaa-lookup/): Retrieve IPv6 (AAAA) records.
- [CNAME Lookup](https://www.nslookup.io/cname-lookup/): Verify canonical name (CNAME) records.
- [MX Record Lookup](https://www.nslookup.io/mx-lookup/): Check mail exchange records and mail server priorities.
- [NS Record Lookup](https://www.nslookup.io/ns-lookup/): View authoritative name servers.
- [TXT Record Lookup](https://www.nslookup.io/txt-lookup/): Inspect TXT records including SPF and domain verification.
- [SOA Record Lookup](https://www.nslookup.io/soa-lookup/): Review Start of Authority (SOA) records.
- [PTR Record Lookup](https://www.nslookup.io/ptr-lookup/): Perform reverse DNS lookups.
- [SRV Record Lookup](https://www.nslookup.io/srv-lookup/): Verify service location records.
- [CAA Record Lookup](https://www.nslookup.io/caa-lookup/): Check Certificate Authority Authorization (CAA) records.
- [DNS Propagation Checker](https://www.nslookup.io/dns-propagation-checker/): Compare DNS responses across multiple global locations.

## Email Authentication Tools

- [SPF Lookup](https://www.nslookup.io/spf-lookup/): Validate SPF records and identify email authentication issues.
- [BIMI Checker](https://www.nslookup.io/bimi-checker/): Verify BIMI records and brand logo configuration.
- [DNS Health](https://www.nslookup.io/dns-health/): Analyze DNS configuration and identify common issues affecting security and reliability.
- [Security Scanner](https://www.nslookup.io/security-scanner/): Scan domains for DNS and security-related misconfigurations.

## Domain & Infrastructure Tools

- [Website to IP Lookup](https://www.nslookup.io/website-to-ip-lookup/): Resolve a website hostname to its IP address.
- [Reverse IP Lookup](https://www.nslookup.io/reverse-ip-lookup/): Discover domains hosted on the same IP address.
- [Website Hosting Checker](https://www.nslookup.io/website-hosting-checker/): Identify a website's hosting provider and infrastructure.
- [SSL Checker](https://www.nslookup.io/ssl-checker/): Inspect SSL/TLS certificates and certificate validity.
- [CSR Generator](https://www.nslookup.io/csr-generator/): Generate Certificate Signing Requests (CSR) for SSL certificates.
- [Certificate Decoder](https://www.nslookup.io/certificate-decoder/): Decode and inspect SSL certificates.
- [Geo Checker](https://www.nslookup.io/geo-checker/): Analyze website geographic and network information.

## Monitoring & Platform

- [DNS Monitoring](https://www.nslookup.io/dns-monitoring/): Continuously monitor DNS records and receive alerts for changes.
- [SSL Monitoring](https://www.nslookup.io/ssl-monitoring/): Monitor SSL certificate expiration and certificate health.
- [Uptime Monitoring](https://www.nslookup.io/uptime-monitoring/): Track website availability and downtime.
- [VMC Monitoring](https://www.nslookup.io/vmc-monitoring/): Monitor Verified Mark Certificates (VMCs).
- [Status Pages](https://www.nslookup.io/status-pages/): Build public status pages for services and infrastructure.
- [Website Insights](https://www.nslookup.io/website-insights/): Monitor and review website infrastructure insights.
- [DNS Change Review](https://www.nslookup.io/dns-change-review/): Review DNS configuration changes before deployment.

## Learning Resources

- [Learning Center](https://www.nslookup.io/learning/): Educational hub covering DNS, email authentication, networking, and internet infrastructure.
- [What is DNS?](https://www.nslookup.io/learning/what-is-dns/): Learn how the Domain Name System works and why it powers the internet.
- [DNS Record Types](https://www.nslookup.io/learning/dns-record-types/): Comprehensive guide to DNS record types including A, AAAA, MX, NS, TXT, SOA, PTR, SRV, and more.
- [What Is DNS Monitoring?](https://www.nslookup.io/learning/what-is-dns-monitoring/): Learn how DNS monitoring detects outages, configuration changes, performance issues, and security threats.
- [What Is DNSSEC?](https://www.nslookup.io/learning/what-is-dnssec/): Learn how DNSSEC authenticates DNS responses with digital signatures and a chain of trust.
- [How to Fix Slow DNS Lookups](https://www.nslookup.io/learning/how-to-fix-slow-dns-lookup/): Find the causes of slow DNS resolution by comparing resolvers, checking authoritative nameservers and records, and testing from different locations.
- [DNS Security Best Practices](https://www.nslookup.io/learning/dns-security-best-practices/): Practical steps to secure your DNS provider, registrar, and records against spoofing, cache poisoning, and hijacking.
- [What Is DNS Cache Poisoning?](https://www.nslookup.io/learning/what-is-dns-cache-poisoning/): Learn how forged DNS responses poison resolver caches and how to prevent malicious redirection.
- [Best SSL Monitoring Tools in 2026](https://www.nslookup.io/learning/best-ssl-monitoring-tools-in-2026/): Compare SSL/TLS certificate monitoring tools by features, pricing, alerts, and security checks.
- [What Is Certificate Transparency?](https://www.nslookup.io/learning/what-is-certificate-transparency/): Learn how CT logs and SCTs make TLS certificate issuance public and how to monitor them for unexpected certificates.
- [Fix DNS_PROBE_FINISHED_NXDOMAIN](https://www.nslookup.io/learning/how-to-fix-dns-probe-finished-nxdomain/): Troubleshoot NXDOMAIN errors caused by DNS settings, caches, resolvers, and domain records.
- [What is a DNS Resolver?](https://www.nslookup.io/learning/what-is-a-dns-resolver/): Understand recursive resolvers and the DNS resolution process.
- [Recursive vs Authoritative DNS](https://www.nslookup.io/learning/recursive-vs-authoritative-dns/): Learn the difference between recursive and authoritative DNS servers.
- [SPF: A Practical Guide](https://www.nslookup.io/learning/spf-a-practical-guide/): Step-by-step guide to implementing SPF records.
- [DKIM: A Practical Guide](https://www.nslookup.io/learning/dkim-a-practical-guide/): Learn how DKIM signs and validates email messages.
- [DMARC: A Practical Guide](https://www.nslookup.io/learning/dmarc-a-practical-guide/): Practical guide to deploying DMARC for domain protection.
- [Email DNS Records](https://www.nslookup.io/learning/email-dns-records/): Guide to the DNS records behind email delivery and authentication, including MX, SPF, DKIM, DMARC, PTR, and more.
- [MX vs SPF vs DMARC vs DKIM vs BIMI](https://www.nslookup.io/learning/mx-vs-spf-vs-dmarc-vs-dkim-vs-bimi/): Compare the most important DNS and email authentication technologies.
- [How to Fix DMARC Failures](https://www.nslookup.io/learning/how-to-fix-dmarc-failures/): Troubleshoot common DMARC authentication failures.
- [How to Read a DMARC Aggregate Report](https://www.nslookup.io/learning/how-to-read-dmarc-aggregate-report/): Learn how to interpret DMARC XML reports.
- [What is an SPF Record?](https://www.nslookup.io/learning/what-is-an-spf-record/): Understand SPF records and email sender authorization.
- [DNS Server Not Responding](https://www.nslookup.io/learning/dns-server-not-responding/): Troubleshooting guide for common DNS resolution issues.

## Platform & Company

- [NsLookup.io Home](https://www.nslookup.io/): DNS lookup, infrastructure monitoring, and security platform.
- [About](https://www.nslookup.io/about/): Learn about the NsLookup.io platform and its mission.
- [Contact Us](https://www.nslookup.io/contact-us/): Contact the NsLookup.io team.
- [MCP](https://www.nslookup.io/mcp/): Model Context Protocol integration for AI assistants.
- [Install](https://www.nslookup.io/install/): Browser installation guides and setup instructions.

## Optional

- [Privacy Policy](https://www.nslookup.io/privacy-policy/): Privacy practices and data handling information.
- [Terms and Conditions](https://www.nslookup.io/terms-and-conditions/): Terms governing the use of the platform.