jck.nl

Nameservers · These nameservers report their software version via version.bind/version.server, which helps attackers find known vulnerabilities: ns1.dnsshop.org: "PowerDNS 1.3.3.7". Hide or replace the version string.

SOA · expire 1d is shorter than 7d; secondaries stop answering too soon when the primary is down. Current values: refresh 1h, retry 10m, expire 1d, negative TTL 15m.

DMARC · DMARC policy is set to 'quarantine'. Consider upgrading to 'reject' for stronger protection once you've verified legitimate emails are passing authentication.

MX · Only one MX record found. For better email reliability, consider adding at least one backup MX server.

DKIM · 1024-bit RSA keys are the minimum and are considered weak today: selector1 (1024 bits), selector2 (1024 bits). Rotate to a 2048-bit key.

TLS · MTA-STS is not configured, so other mail servers fall back to unencrypted delivery when TLS fails or is stripped by an attacker. Publish a _mta-sts TXT record and a policy at https://mta-sts.<domain>/.well-known/mta-sts.txt.