DNS Gurus
Open Cached · just now
78/100 SECURITY SCORE

Certificate Information

Subject
CN=mail.synyx.net
Issuer
C=US, O=Let's Encrypt, CN=R13
Valid From
October 07, 2025
Valid Until
January 05, 2026 55 days
Public Key
RSA 2048 bit Adequate
Signature Algorithm
SHA256-RSA
SHA-256 Fingerprint
BD:C1:72:B1:64:00:09:EC:71:8A:F1:31:D2:13:CB:87:B0:55:9D:62:60:F2:18:FB:C6:8B:FB:D2:CF:91:81:CC
Alternative Names
9 domains

Security Configuration

TLS Protocols
TLS 1.2 TLS 1.3
Forward Secrecy
Supported (Modern clients use PFS)

HTTP Security Headers

Status
Strict-Transport-Security
Missing
Not configured
Content-Security-Policy
Missing
Not configured
X-Frame-Options
Good
sameorigin
X-Content-Type-Options
Missing
Not configured
Referrer-Policy
Missing
Not configured
Permissions-Policy
Missing
Not configured
Recommendations
  • • Add Strict-Transport-Security header with max-age of at least 1 year
  • • Add Content-Security-Policy header to prevent XSS attacks
  • • Add X-Content-Type-Options: nosniff
  • • Add Referrer-Policy header (recommended: strict-origin-when-cross-origin)
  • • Consider adding Permissions-Policy to control browser features

CAA Records (Certificate Authority Authorization)

CAA Records
Not Configured (Any CA can issue certificates)
CAA Issues
  • • No CAA records configured - any CA can issue certificates
Recommendations
  • • Implement CAA records to restrict which CAs can issue certificates for your domain
  • • This adds an extra layer of security against unauthorized certificate issuance
  • • Example: Add CAA record 'example.com. CAA 0 issue "letsencrypt.org"'
  • • Consider adding 'iodef' record to receive security incident reports