uni-greifswald.de

Delegation · all IPv4 addresses are in 141.53.10.0/24. A single network failure takes all nameservers down; RFC 2182 recommends topologically separate networks (anycast setups are an exception).

Delegation · None of the nameservers has an IPv6 address, so IPv6-only resolvers can't reach them.

Nameservers · These nameservers report their software version via version.bind/version.server, which helps attackers find known vulnerabilities: dns1.uni-greifswald.de: "9.20.29-1~deb13u1-Debian"; dns2.uni-greifswald.de: "9.20.29-1~deb13u1-Debian". Hide or replace the version string.

SOA · negative caching TTL (minimum) 2d is outside 5m–1d (RFC 2308 recommends 1–3 hours). Current values: refresh 1d, retry 2h, expire 21d, negative TTL 2d.

DKIM · The _domainkey name exists but no DKIM key was found under the common selectors. Selectors are provider-specific; check yours with -selector.

MX · The following MX hosts could not be resolved to IPv6 addresses: mx1.uni-greifswald.de, mx2.uni-greifswald.de

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.

TLS · MTA-STS or DANE is used without TLS-RPT, so you get no reports when senders fail to deliver because of TLS problems. Publish _smtp._tls TXT "v=TLSRPTv1; rua=mailto:...".