DNS (Domain Name System) is the internet's phone book — it translates human-readable domain names like devnovatools.com into IP addresses that computers use to communicate. Understanding DNS is essential for debugging deployment issues, configuring email and managing infrastructure.
How DNS Resolution Works
When you type a URL in your browser, a complex lookup happens in milliseconds:
- Browser cache — Has this domain been looked up recently?
- OS resolver cache — Check the local system DNS cache
- Recursive resolver — Your ISP or configured DNS server (8.8.8.8, 1.1.1.1)
- Root nameservers — 13 root servers know which TLD servers (.com, .org) to ask
- TLD nameservers — The .com nameserver knows which authoritative server has the answer
- Authoritative nameserver — Returns the actual DNS record
Use our DNS Lookup tool to query any record type for any domain in real time using Cloudflare's DNS over HTTPS.
Essential DNS Record Types
A Record — IPv4 Address
The most common record. Maps a hostname to an IPv4 address. Example: devnovatools.com → 104.21.1.1. This is what browsers use to connect to your web server.
AAAA Record — IPv6 Address
Same as A record but for IPv6 addresses. Modern servers should have both A and AAAA records for dual-stack compatibility.
CNAME — Canonical Name
An alias that points to another hostname instead of an IP. Example: www.example.com → example.com. CDN providers use CNAMEs to point your domain to their servers. Important: You cannot use a CNAME on the root domain (example.com) — use an ALIAS or ANAME record there.
MX Record — Mail Exchange
Specifies which servers handle email for a domain. MX records have a priority value — lower numbers get tried first. If you're having email delivery issues, check MX records with our DNS Lookup tool by selecting the MX type.
TXT Record — Text
Stores arbitrary text — used for domain verification (Google Search Console, AWS), SPF records (email authentication) and DKIM keys. Format: v=spf1 include:sendgrid.net ~all.
NS Record — Nameservers
Specifies which nameservers are authoritative for a domain. When you move a domain between registrars or change DNS providers, you update NS records. NS changes take the longest to propagate.
Understanding TTL (Time to Live)
TTL is how long DNS resolvers cache a record (in seconds). A TTL of 3600 means resolvers cache the record for 1 hour before checking again.
Before changing DNS: Lower your TTL to 300 (5 minutes) 24 hours before making changes. This minimizes downtime during propagation. After changes are stable, raise it back to 3600 or higher for performance.
Debugging DNS Issues
When DNS isn't working as expected, follow this debugging process:
- Check the record directly — Use our DNS Lookup tool to query the record type you're troubleshooting
- Check from multiple locations — DNS propagation varies by region. Use tools like dnschecker.org to check from multiple countries
- Verify nameservers — Are NS records pointing to the right DNS provider?
- Check TTL — Are you seeing a cached old record? Wait for TTL to expire
- Flush local cache — Run
ipconfig /flushdns(Windows) orsudo dscacheutil -flushcache(Mac)
DNS and SSL Certificates
SSL certificate issuance requires DNS validation — adding a TXT record to prove you own the domain. Let's Encrypt uses this for automatic certificate renewal. Use our SSL Certificate Checker to verify your certificate is properly installed after DNS changes.
Common DNS Mistakes
- Using CNAME on root domain (breaks MX and other records)
- Forgetting to add AAAA records when adding A records
- Not lowering TTL before DNS migration
- Pointing MX records to an IP instead of a hostname
- Incorrect SPF/DKIM TXT records causing email to go to spam