weizenbaum-institut.de

Delegation · all IPv4 addresses are in 193.174.75.0/24; all IPv6 addresses are in 2001:638:d::/48. A single network failure takes all nameservers down; RFC 2182 recommends topologically separate networks (anycast setups are an exception).

SOA · retry 1h should be shorter than refresh 1h. Current values: refresh 1h, retry 1h, expire 21d, negative TTL 1h.

DNSSEC · The zone is not signed with DNSSEC, so answers can be spoofed. Enable DNSSEC at your DNS provider and publish the DS record at your registrar.

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

DNSSEC · DNSSEC is not enabled for this domain. Consider enabling DNSSEC to protect against DNS spoofing attacks.

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

DMARC · DMARC subdomain policy is sp=none, so spoofed mail from subdomains is not blocked. Consider sp=quarantine or sp=reject.

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.