DNS Lookup

DNS Lookup (Domain Name System) translates human-readable domain names into IP addresses and retrieves various DNS records that control how domains function. Think of DNS as the internet's phone book. When you visit example.com, DNS lookup finds its IP address (93.184.216.34) so your browser can connect. Key DNS record types: A records map domains to IPv4 addresses (example.com → 93.184.216.34). AAAA records map to IPv6 addresses (example.com → 2606:2800:220:1:248:1893:25c8:1946). MX records specify mail servers for email delivery (mail.example.com with priority 10). TXT records store text data for SPF, DKIM, domain verification, and other purposes. CNAME records create domain aliases (www.example.com → example.com). NS records identify authoritative nameservers for the domain. SOA records contain administrative information about the DNS zone. PTR records perform reverse DNS (IP to domain). SRV records specify service locations. Understanding these records is essential for website hosting, email configuration, domain verification, and troubleshooting connectivity issues.

Enter the domain name you want to investigate and select the record type or use 'ANY' to retrieve all records. For website not loading: Check A/AAAA records to verify they point to the correct server IP. No A record means the domain can't resolve. Wrong IP means DNS hasn't updated or points to the wrong server. For email delivery failures: Query MX records to confirm mail servers are configured. Missing MX records mean emails can't be delivered. Verify priorities (lower numbers = higher priority). For DNS propagation after changes: Query from multiple locations to see if updates have spread globally. DNS changes take 1-48 hours to propagate depending on TTL (Time To Live) settings. For subdomain issues: Check if subdomains have proper A/CNAME records. For domain verification: Look up TXT records to confirm verification codes for services like Google Workspace, Office 365, or SSL certificates. For email authentication: Check TXT records for SPF (starts with 'v=spf1'), DKIM (selector._domainkey.example.com), and DMARC (_dmarc.example.com). Common errors: NXDOMAIN means domain doesn't exist, SERVFAIL indicates DNS server problems, and timeouts suggest network or firewall issues.

SPF (Sender Policy Framework) is a TXT record listing IP addresses/servers authorized to send email for your domain, preventing email spoofing. Example: v=spf1 ip4:203.0.113.45 include:_spf.google.com ~all. The ~all means soft fail for unauthorized servers, while -all is hard fail (reject). Use DNS Lookup on your domain's TXT records to verify SPF exists and includes all your mail servers. Limit to 10 DNS lookups maximum (SPF limitation). DKIM (DomainKeys Identified Mail) adds cryptographic signatures to emails, verifying they haven't been altered. DKIM records are at selector._domainkey.yourdomain.com (e.g., google._domainkey.example.com). Look up this subdomain's TXT record to see the public key starting with v=DKIM1; k=rsa; p=.... DMARC (Domain-based Message Authentication) specifies what to do when SPF/DKIM fail and where to send reports. Found at _dmarc.yourdomain.com TXT record: v=DMARC1; p=quarantine; rua=mailto:dmarc@example.com. The p= policy can be none (monitor only), quarantine (spam folder), or reject (block). Proper configuration of all three dramatically improves email deliverability and protects your domain from phishing attacks using your name.

DNS propagation is the time it takes for DNS changes to spread across the internet's thousands of DNS servers. When you update DNS records, changes don't happen instantly globally. Typical propagation takes 1-48 hours, though most changes complete within 4-8 hours. The speed depends on TTL (Time To Live) values set in DNS records, measured in seconds. A TTL of 3600 means DNS servers cache the record for 1 hour before checking for updates. Lower TTL (300 = 5 minutes) enables faster propagation but increases DNS query load. Why different results occur: Your ISP's DNS server may have cached old records while another DNS server (like Google's 8.8.8.8) has the new ones. Different geographic regions update at different times. Some DNS servers ignore TTL and cache longer. Best practices for DNS changes: Lower TTL to 300 (5 minutes) 24-48 hours before planned changes. Make your DNS updates. Wait for old TTL period to expire. Raise TTL back to 3600-86400 (1-24 hours) for normal operation. Test propagation by querying different DNS servers: Google (8.8.8.8), Cloudflare (1.1.1.1), your ISP's DNS, and public DNS checkers. Clear your local DNS cache: Windows (ipconfig /flushdns), macOS (sudo dscacheutil -flushcache), Linux (sudo systemd-resolve --flush-caches).

NOERROR (successful): Query succeeded and returned records. This is the normal, expected response. NXDOMAIN (Non-Existent Domain): The domain doesn't exist in DNS. Fixes: Verify correct spelling, ensure domain is registered and not expired, check that nameservers are properly configured at your registrar, wait for propagation if newly registered. SERVFAIL (Server Failure): DNS server encountered an error processing your request. Causes: authoritative nameserver is down, DNSSEC validation failure, misconfigured DNS zone, circular CNAME references. Fix by checking nameserver status, reviewing DNS configuration, or contacting DNS provider. REFUSED: DNS server refused the query. Usually means the server doesn't allow queries from your location or for that zone. Try different DNS servers. TIMEOUT: No response received from DNS server. Indicates network connectivity issues, firewall blocking DNS (port 53), or DNS server is down. Test with alternative DNS servers like 8.8.8.8. No records found (empty response): Domain exists but requested record type doesn't. For example, querying MX records on a domain with no email configuration. FORMERR (Format Error): Query was malformed. Usually indicates issues with DNS query syntax. NOTIMP (Not Implemented): DNS server doesn't support the requested operation.

For website hosting, create an A record pointing your root domain (@) to your web server's IPv4 address: example.com → 203.0.113.45. Add another A record for www subdomain: www.example.com → 203.0.113.45, or use a CNAME record: www → example.com (note: CNAME can't be used on root domain). For IPv6, add AAAA records. For email with Google Workspace/Gmail: Add MX records: ASPMX.L.GOOGLE.COM (priority 1), ALT1.ASPMX.L.GOOGLE.COM (priority 5), ALT2.ASPMX.L.GOOGLE.COM (priority 5), ALT3.ASPMX.L.GOOGLE.COM (priority 10), ALT4.ASPMX.L.GOOGLE.COM (priority 10). Add SPF TXT record: v=spf1 include:_spf.google.com ~all. Configure DKIM by adding the TXT record provided by Google at google._domainkey.example.com. Add DMARC TXT record at _dmarc.example.com: v=DMARC1; p=none; rua=mailto:admin@example.com. For CDN services like Cloudflare: Point A records to Cloudflare's IPs (they provide specific addresses) or use CNAME to their hostname. For subdomain services: Create CNAME pointing to service provider (e.g., shop.example.com → shops.shopify.com). Always note the TTL recommended by your provider and use DNS Lookup to verify records appear correctly after configuration.