What is DNS Lookup?
DNS Lookup is the query process that converts domain names (like example.com) to IP addresses and other DNS information. This tool allows you to easily check various DNS records including A (IPv4), AAAA (IPv6), MX (mail), TXT, NS (nameserver), CNAME, and SOA. Used for DNS configuration verification, troubleshooting, and domain information investigation.
What's the difference between A records and AAAA records?
A records convert domain names to IPv4 addresses (e.g., 192.0.2.1). IPv4 is a 32-bit address system with about 4.3 billion addresses. AAAA records (quad-A) convert domain names to IPv6 addresses (e.g., 2001:db8::1). IPv6 is a 128-bit address system with virtually infinite address space, solving IPv4 address exhaustion. Modern websites often have both record types to support dual-stack environments.
What are MX records? How do they relate to email sending?
MX records (Mail Exchange Records) specify mail servers that receive email for that domain. You can set multiple MX records, each with a priority value. Lower numbers indicate higher priority, and mail is delivered first to high-priority servers. Example: if example.com has two MX records '10 mail1.example.com' and '20 mail2.example.com', mail1 is used preferentially, and if mail1 is down, it falls back to mail2. When email isn't being delivered, checking MX records is the first troubleshooting step.
What are TXT records used for?
TXT records store arbitrary text information about a domain. Main uses include: **SPF (Sender Policy Framework)**: validating mail sender server legitimacy, **DKIM (DomainKeys Identified Mail)**: email digital signatures, **DMARC (Domain-based Message Authentication, Reporting & Conformance)**: email authentication policy, **Domain ownership verification**: for Google Search Console, Google Workspace, SSL certificate issuance authentication, **Other configuration info**: site authentication tokens, service integration info, etc. Example SPF record: 'v=spf1 include:_spf.example.com ~all'
What's the relationship between NS records and nameservers?
NS records (Name Server Records) specify authoritative DNS servers (nameservers) for that domain. When registering a domain, setting nameservers at the registrar makes those nameservers manage DNS information. Typically, multiple nameservers (e.g., ns1.example.com, ns2.example.com) are set for redundancy. During domain transfers or hosting changes, NS records must be changed to new nameservers. After changes, propagation to DNS servers worldwide can take up to 48 hours.
When should CNAME records be used?
CNAME records (Canonical Name Records) define domain aliases. For example, if 'www.example.com' is set as a CNAME for 'example.com', www-prefixed access is handled correctly. Main uses: **Subdomain forwarding**: blog.example.com → hosting-provider.com, **CDN configuration**: cdn.example.com → cdn-provider.net, **Load balancers**: api.example.com → lb.cloud-provider.com. Cautions: CNAMEs cannot be set for root domains (example.com), only subdomains (www.example.com, etc.). Also, you cannot coexist CNAME with other records (A, MX, etc.) at the same name.
How long does it take for DNS query results to propagate?
Time for DNS changes to propagate worldwide is primarily determined by TTL (Time To Live). If TTL is 3600 seconds (1 hour), DNS resolvers cache old information for up to 1 hour. Setting short TTLs before DNS changes (e.g., 300 seconds = 5 minutes) speeds up post-change propagation. Typically, DNS changes propagate in minutes to hours, but some ISPs may take up to 48 hours. This tool allows you to immediately verify changes are correctly configured by querying authoritative DNS servers in real-time.
How does the DNS Lookup tool work?
This tool retrieves DNS information through these steps: 1) User specifies domain name and record types, 2) Browser sends request to PHP backend, 3) Server executes DNS queries using PHP functions like dns_get_record(), 4) Retrieves latest DNS information from authoritative DNS servers, 5) Formats results and returns to browser, 6) JavaScript displays results in user-friendly format. It doesn't complete in the browser; DNS queries are executed server-side for accurate, up-to-date information. Entered domain names are not logged, protecting privacy.