zhihu.com

Delegation · The addresses at the parent (glue) differ from the addresses in the zone: ns3.dnsv5.com (glue 1.12.0.17, 1.12.0.18, 1.12.14.17, 1.12.14.18, 101.227.168.52, 108.136.87.44, 163.177.5.52, 220.196.136.52, 2402:4e00:1470:2::f, 35.165.107.227, zone 13.37.58.163, 1.12.14.18, 1.12.0.18, 162.62.49.74, 1.12.14.17, 18.134.75.163, 15.160.102.38, 1.12.0.17, 163.177.5.52, 240d:c000:3011::10); ns4.dnsv5.com (glue 1.12.0.16, 1.12.0.19, 1.12.14.16, 1.12.14.19, 117.135.128.152, 124.64.205.152, 13.37.58.163, 2402:4e00:111:fff::8, 49.7.107.152, zone 1.12.0.16, 13.48.202.4, 1.12.0.19, 63.34.1.181, 1.12.14.19, 162.62.49.12, 1.12.14.16, 18.194.2.137, 240d:c000:3011::f). Update the glue at your registrar.

Nameservers · These nameservers report their software version via version.bind/version.server, which helps attackers find known vulnerabilities: ns3.dnsv5.com: "DNSPod AUTHORITY DNS 7.3.2512.01"; ns4.dnsv5.com: "DNSPod AUTHORITY DNS 7.3.2512.01". Hide or replace the version string.

SOA · negative caching TTL (minimum) 3m is outside 5m–1d (RFC 2308 recommends 1–3 hours). Current values: refresh 1h, retry 3m, expire 14d, negative TTL 3m.

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 · The following MX hosts could not be resolved to IPv6 addresses: mxbiz1.qq.com, mxbiz2.qq.com

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

DMARC · These report addresses are in another domain that has not agreed to receive your reports, so receivers will not send them: mailto:mailauth-reports@qq.com (needs zhihu.com._report._dmarc.qq.com). Ask the report provider to publish the record, or check the address.

MX · These MX addresses have no PTR record, which many receivers treat as a spam signal: 103.86.78.2 (mxbiz1.qq.com), 103.86.78.3 (mxbiz1.qq.com), 43.154.252.16 (mxbiz2.qq.com), 43.154.252.202 (mxbiz2.qq.com). Ask your hosting provider to set one.

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.