zhihu.com

ns3.dnsv5.com, ns4.dnsv5.com

Found

Parent zone

com

Delegation from

a.gtld-servers.net (192.5.6.30)

NS at the parent

ns3.dnsv5.com, ns4.dnsv5.com

NS in the zone

ns3.dnsv5.com, ns4.dnsv5.com

Checks

• i

  2 nameservers

  Two nameservers meet the minimum; RFC 2182 recommends three or more for important zones: ns3.dnsv5.com, ns4.dnsv5.com.

  #6
• ✓ Parent and zone agree #7

  The parent delegation and the zone's NS records list the same nameservers.
• !

  Glue differs from the zone

  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.

  #8
• ✓ All names resolve #9

  Every nameserver name has an address and is not an alias.
• i

  One address family in one network

  all IPv6 addresses are in 240d:c000:3011::/48, while the other address family is spread over several networks.

  #10
• ✓ 3 autonomous systems #11

  The nameservers are spread over: AS132203 (TENCENT-NET-AP-CN - Tencent Building, Kejizhongyi Avenue, CN): 12 addresses; AS136958 (UNICOM-GuangZhou-IDC - China Unicom Guangdong IP network, CN): 1 address; AS16509 (AMAZON-02 - Amazon.com, Inc., US): 6 addresses.
• i

  All nameserver names under .com

  All nameserver names are under one TLD, so a problem with that TLD also makes the nameservers unreachable. Some operators use names under two TLDs for extra resilience.

  #12
• ✓ All reachable over IPv6 #13

  Every nameserver has an IPv6 address.

19 of 19 addresses answer authoritatively

Found

Checks

• ✓ All respond #14

  All 19 nameserver addresses answered.
• ✓ All authoritative #15

  Every responding nameserver answers authoritatively for the zone.
• ✓ No recursion #16

  The nameservers do not answer recursive queries for other domains.
• !

  Software version disclosed

  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.

  #17
• ✓ Zone transfers refused #18

  No nameserver allows a zone transfer to the public.
• ✓ TCP supported #19

  All nameservers answer over TCP.
• ✓ EDNS supported #20

  All nameservers support EDNS(0).
• ✓ Public addresses #21

  All nameserver addresses are publicly routable.

serial 1792522427 · primary ns3.dnsv5.com

Found

Primary (MNAME)

ns3.dnsv5.com

Contact (RNAME)

enterprise3dnsadmin.dnspod.com

Serial

1792522427

Refresh / retry

3600 s / 180 s

Expire

1209600 s

Negative TTL

180 s

Serial per nameserver

Checks

• ✓ Serial 1792522427 everywhere #22

  All nameservers serve the same version of the zone.
• !

  Unusual SOA timers

  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.

  #23
• ✓ Primary is a public nameserver #24

  The primary nameserver ns3.dnsv5.com is one of the listed nameservers.
• ✓ Contact enterprise3dnsadmin@dnspod.com #25

  The SOA RNAME enterprise3dnsadmin.dnspod.com means enterprise3dnsadmin@dnspod.com.
• ✓ Timestamp serial #26

  The serial 1792522427 is a Unix timestamp (2026-10-20 18:53 UTC).

Not signed

Found

Validated by resolver

no

Checks

• !

  Not signed

  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.

  #27