DNS Analysis

The DNS Analysis feature in SiteOne Crawler examines how domain names are resolved to IP addresses, providing valuable insights into your website’s DNS configuration and potential DNS-related issues.

Key Features

The DNS analyzer provides detailed information about:

• DNS Resolution Chain: The complete resolution path for domain names
• IPv4 Support: Detection and validation of IPv4 address resolution
• IPv6 Support: Detection and validation of IPv6 address resolution
• CNAME Records: Identification of domain aliases through CNAME chains
• DNS Server Information: Details about the DNS servers used for resolution

DNS Information Display

The analyzer presents DNS information in a clear, hierarchical format:

DNS resolving tree
------------------------------------------------------------------------
example.com
  IPv4: 93.184.216.34

DNS server: 192.168.1.1

For sites with CNAME records and more complex DNS configuration:

DNS resolving tree
------------------------------------------------------------------------
blog.example.com
  CNAME: blog-cdn.example.net
    CNAME: cdn-endpoint.cdn-provider.com
      IPv4: 151.101.1.195
      IPv4: 151.101.65.195
      IPv6: 2a04:4e42:400::323
      IPv6: 2a04:4e42:600::323

DNS server: 8.8.8.8

Summary Information

The DNS analyzer also adds summary entries to provide quick insights:

• IPv4 Status: Confirms if the domain properly resolves to IPv4 addresses
• IPv6 Status: Confirms if the domain has IPv6 support
• CNAME Chain: Shows the full alias chain if the domain uses CNAMEs

Example summary entries:

DNS IPv4 OK: Domain example.com resolved to 93.184.216.34 (DNS server: 192.168.1.1)
DNS IPv6: Domain example.com does not support IPv6 (DNS server: 192.168.1.1)

How It Works

The DNS analyzer employs multiple resolution methods to ensure accurate results:

1. Command-line Tools: Uses native nslookup or dig commands when available
2. PHP Functions: Falls back to PHP’s dns_get_record() function if command-line tools are unavailable
3. Result Parsing: Parses and organizes DNS resolution results into a structured format
4. IPv4/IPv6 Detection: Specifically checks for both IPv4 and IPv6 address records
5. CNAME Traversal: Follows and documents the complete CNAME chain

Practical Benefits

DNS analysis provides several practical benefits:

• DNS Configuration Validation: Verify that DNS is correctly configured
• IPv6 Readiness: Confirm whether your site supports IPv6
• DNS Resolution Issues: Identify problems with domain resolution
• CDN Validation: Verify that CDN configurations are correctly set up
• Multisite Setup: Understand the DNS architecture of complex multisite deployments

Considerations and Limitations

• DNS Caching: Results reflect the state of DNS at the time of the crawl and may be affected by local DNS caching
• Tool Availability: The accuracy of results may vary depending on the availability of command-line tools like nslookup or dig
• Network Environment: Results may differ based on the network environment where the crawler is run

💡Further Development Ideas

Future enhancements to the DNS analysis could include:

• TTL Analysis: Evaluation of TTL (Time-to-Live) values for DNS records
• Authoritative Servers: Information about the authoritative DNS servers for the domain
• DNS Security: Checks for DNSSEC implementation
• Propagation Testing: Testing DNS resolution from multiple global locations
• Historical Comparison: Tracking changes in DNS configuration over time