DNS & Domain Agent — SiteSentinel

What This Agent Does

The DNS & Domain Agent validates DNS configuration and email security settings, including MX records, SPF, DKIM, and DMARC policies that protect against email spoofing.

Category Information

Property	Value
Category Name	`DNS & Domain`
Category Icon
Source File	`src/checks/dns.check.js`

Checks Performed

DNS Resolution

Verifies that the domain resolves to valid IP addresses (A/AAAA records).

MX Records

Checks for mail exchange servers configured for the domain.

SPF Record

Validates Sender Policy Framework to prevent email spoofing.

DKIM

Checks for DomainKeys Identified Mail signatures.

DMARC Policy

Validates Domain-based Message Authentication policy.

CAA Records

Checks Certificate Authority Authorization records.

Data Sources

Libraries Used

dns — Node.js built-in DNS module
dns.promises — Promise-based DNS lookups

DNS Query Types

const dns = require('dns').promises;

// A records (IPv4)
const aRecords = await dns.resolve4(hostname);

// AAAA records (IPv6)  
const aaaaRecords = await dns.resolve6(hostname);

// MX records
const mxRecords = await dns.resolveMx(hostname);

// TXT records (for SPF, DKIM, DMARC)
const txtRecords = await dns.resolveTxt(hostname);
const dmarcRecords = await dns.resolveTxt(`_dmarc.${hostname}`);

Email Security Checks

SPF Record Format

v=spf1 include:_spf.google.com ~all

Specifies which servers are allowed to send email for the domain.

DMARC Record Format

v=DMARC1; p=reject; rua=mailto:dmarc@example.com

Defines policy for handling failed SPF/DKIM checks.

Return Value

{
  category: 'DNS & Domain',
  icon: 'globe',
  score: 0-100,
  checks: [
    {
      name: 'DNS Resolution',
      status: 'pass',
      description: 'Domain resolves to 1.2.3.4',
      severity: 'critical'
    },
    {
      name: 'SPF Record',
      status: 'pass' | 'fail' | 'warn',
      description: 'SPF record found and valid',
      severity: 'high'
    },
    // ... more checks
  ]
}