Back to Blog

How to Check Website DNS

2025-09-23

How to Check Website DNS

The Domain Name System (DNS) is like the phonebook of the internet—it translates human-readable domain names into IP addresses that computers use to communicate. When DNS fails, even a perfectly working server can appear offline.

Understanding and monitoring DNS is essential for web developers, system administrators, and anyone who manages a website.

Why DNS Matters for Website Availability

  • DNS Resolution: If a browser cannot resolve a domain to an IP, the site won't load.
  • Global Accessibility: DNS propagation issues may cause some regions to see the site as down.
  • Impact on Services: Email, APIs, and other services tied to the domain rely on correct DNS configuration.

Common DNS Issues

  1. Incorrect A/AAAA Records

    • The domain points to the wrong IP address.
    • Can happen after server migrations or hosting changes.

  2. Expired Domain

    • If the domain registration lapses, DNS resolution will fail globally.

  3. Misconfigured CNAME or MX Records

    • Can affect subdomains, email, or redirect services.

  4. DNS Propagation Delays

    • Changes to DNS records can take hours to propagate worldwide.
    • During propagation, some users may see the old IP while others see the new one.

Tools to Check DNS

1. Command-Line Tools

nslookup

nslookup example.com
  • Shows IP address and DNS server used.
  • Quick way to verify if a domain resolves.

dig

dig example.com
  • Provides detailed DNS record info (A, AAAA, MX, CNAME, TXT).
  • Useful for debugging propagation issues.

2. Online DNS Checkers

  • isitoffline.com – quickly checks if a website is reachable.
  • MXToolbox – detailed DNS lookup for multiple record types.
  • DNSChecker – shows DNS propagation across multiple locations.

Example: Checking A Record

dig example.com A

Example output:

; <<>> DiG 9.16.1-Ubuntu <<>> example.com A
;; ANSWER SECTION:
example.com.  3600  IN  A  93.184.216.34

This shows that the domain example.com resolves to IP 93.184.216.34.

Troubleshooting DNS Issues

  • No IP Returned: Check domain registration and hosting provider settings.
  • Wrong IP: Update the A/AAAA record to the correct server IP.
  • Propagation Delays: Use online propagation checkers to see if changes have spread globally.
  • Temporary Outages: Some DNS providers may experience short-term failures—monitor and retry.

Real-World Tips

  • Always use reputable DNS providers (e.g., Cloudflare, Google DNS).
  • Keep TTL (Time-To-Live) values reasonable; too long may delay updates.
  • Monitor your DNS along with website status for complete uptime analysis.

Conclusion

DNS plays a critical role in website accessibility. By understanding DNS records, using tools like nslookup and dig, and checking propagation, you can quickly determine whether a website is truly down or if the problem lies in DNS configuration.

Pro Tip: Combining DNS checks with HTTP status and ping tests gives a complete picture of a website's availability.

[ 广告加载中... ]