DNS Resolution Errors

What is DNS?

DNS (Domain Name System) translates domain names like example.com into IP addresses like 93.184.216.34. When DNS fails, browsers can't connect to servers.

ERR_NAME_NOT_RESOLVED
This site can't be reached
example.com's server IP address could not be found.

Common DNS Errors

Diagnosing DNS Issues

# Basic DNS lookup
dig example.com
nslookup example.com

# Query specific DNS server
dig @8.8.8.8 example.com
dig @1.1.1.1 example.com

# Get all record types
dig example.com ANY

# Check specific record types
dig example.com A      # IPv4 address
dig example.com AAAA   # IPv6 address
dig example.com MX     # Mail servers
dig example.com NS     # Name servers
dig example.com CNAME  # Alias

# Trace DNS resolution path
dig +trace example.com

# Check local DNS cache (macOS)
sudo dscacheutil -flushcache

# Check local DNS cache (Windows)
ipconfig /displaydns
ipconfig /flushdns

NXDOMAIN - Domain Not Found

The authoritative DNS server says this domain doesn't exist. Causes:

• Typo in domain: Check spelling carefully
• Domain expired: Renew through registrar
• Nameservers not set: Configure NS records at registrar
• Recently registered: Wait for propagation

# Check if domain is registered
whois example.com | grep -i "expir"

# Check nameservers at registrar level
dig NS example.com @a.gtld-servers.net

SERVFAIL - Server Failure

The DNS server encountered an error processing the query. Causes:

• DNSSEC validation failed: Incorrect DNSSEC signatures
• Nameserver misconfigured: Zone file has errors
• Upstream DNS issue: Try a different resolver

# Check DNSSEC status
dig +dnssec example.com

# Try without DNSSEC validation
dig +cd example.com  # Check Disabled

# Test with different resolvers
dig @8.8.8.8 example.com
dig @1.1.1.1 example.com
dig @9.9.9.9 example.com

DNS Propagation

DNS changes can take up to 48 hours to propagate globally due to caching.

# Check current TTL
dig example.com | grep -E "^example.com"
# Output: example.com.  300  IN  A  93.184.216.34
#                       ^^^  TTL in seconds (5 minutes)

# Before making changes, lower TTL to 60-300 seconds
# Then wait for old TTL to expire before making the change

Common Fixes

• Flush local cache: Clear your computer's DNS cache
• Try different resolver: Use 8.8.8.8 or 1.1.1.1
• Check registrar settings: Verify NS records are correct
• Verify zone file: Check for syntax errors
• Wait for propagation: Give it 1-48 hours

DNS Providers