DNS Lookup

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Queries various DNS records of a domain, including A, AAAA, CNAME, MX, NS, TXT, SRV, CAA, HTTPS, SVCB, and SPF, to help troubleshoot domain resolution issues

Introduction

The DNS Lookup tool queries the various resolution records of a domain and returns complete information for all major record types at once, including A, AAAA, CNAME, MX, NS, TXT, SRV, CAA, HTTPS, SVCB, and SPF. Enter a domain and the tool issues each DNS query in turn, then groups and displays the results so network administrators, DevOps engineers, and developers can troubleshoot resolution problems and verify record configuration.

Common DNS record types explained:

  • A record: The most common type, pointing a domain to an IPv4 address such as 8.8.8.8
  • CNAME: Points a domain to another domain name and resolves it the same way
  • MX: Used for mail servers; the relevant parameters are usually provided by your email registrar
  • TXT: Holds additional text information, commonly used for domain verification
  • AAAA: Points a domain to an IPv6 address such as 2404:6800:4012:3::200e
  • NS: Nameserver record; lets you delegate a domain to another DNS provider for resolution
  • CAA: Specifies the certificate authorities (CA) allowed for a domain, reducing issuance risk
  • SRV: Identifies a server providing a particular service, common in Microsoft directory management. Format: "service name.protocol type", such as _sip._tcp
  • HTTPS: HTTPS service binding record that improves HTTPS security and performance
  • SVCB: A newer service binding record type that lets a service point to multiple clients and attach custom parameter values
  • SPF: Specifies which servers are allowed to send email, providing an effective anti-spam solution

Technical Principles

DNS (the Domain Name System) resolves domain names to IP addresses through a distributed, hierarchical structure. When the tool sends a query, it dispatches a DNS message of a specific TYPE to an upstream recursive resolver, containing the queried domain and record type.

When parsing the response message, the tool reads the header counters (such as ANCOUNT), skips the question section, and resolves any domain compression pointers that appear in the RDATA so it can correctly reconstruct the target names of CNAME, NS, MX, and SRV records. For TXT records it merges any split string segments; for SVCB/HTTPS it further parses additional parameters such as alpn, port, and ipv4hint.

Use Cases

  • Domain troubleshooting: when a site is unreachable, confirm whether resolution is working via A/AAAA/CNAME records
  • Mail configuration: verify MX, SPF, and TXT records to resolve send/receive and anti-spam issues
  • Certificate issuance: check CAA records to confirm the allowed certificate authorities and avoid issuance failures
  • Service discovery: query SRV records to locate the server and port for a service such as _sip._tcp
  • CDN onboarding: use NS and A records to confirm a domain has switched to the target DNS provider
  • Security audit: inspect HTTPS/SVCB records to assess modern transport optimization configuration

Frequently Asked Questions

Q: What is the difference between an A record and a CNAME record?
A: An A record points a domain directly to an IPv4 address, while a CNAME points a domain to another domain name, which is then resolved further. CNAME is often used to point a www subdomain to the apex domain, but it cannot be used at the apex itself and must not conflict with other records.
Q: Why does the result not show a particular record type?
A: If a record type is not configured in the authoritative DNS, the tool returns an empty "no record" result. It is also possible that the upstream recursive resolver does not return the newer HTTPS/SVCB records, in which case try a different resolver or cross-check with a tool that supports them.
Q: How are SPF and TXT records related?
A: SPF records are stored as TXT records (of the form v=spf1 ...) that declare which servers are allowed to send mail. When you query TXT, the tool returns all text; when you query SPF, it automatically filters for records beginning with v=spf1.

Typical Usage

Query the A and MX records of a domain:

Input: example.com A
Output:
  A records (example.com):
    - 93.184.216.34  (TTL 3600)

Input: example.com MX
Output:
  MX records (example.com):
    - priority 0 → .  (TTL 3600)

Query the CAA record of a domain:

Input: google.com CAA
Output:
  CAA records (google.com):
    - flags=0 issue=pki.goog  (TTL 3600)

Related Tools

This tool belongs to the same network group as IP Lookup, My IP Address, and HTTP Status Checker: DNS resolves a domain into an IP, while IP Lookup analyzes the properties of that IP in depth and HTTP Status Checker tells you whether a page is reachable. When troubleshooting network issues, it is often used alongside URL Decoder and URL Encoder; for validating data you can also pair it with MD5 and Base Converter.

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