liangzuo.com

Checked 22 October 2026, 09:35 UTC · via 8.8.8.8
✗Problems found
17 passed 5 warnings 2 failed 7 info

Registration

info

.com generic · Bizcn.com, Inc. · expires 2027-04-13

Found

TLD
.com (generic)
ICANN policies apply
yes
Registrar
Bizcn.com, Inc.
Registered
13 April 2007
Last changed
28 February 2026
Expires
13 April 2027
Status
active
Registry nameservers
ns1.dns.com.cn, ns2.dns.com.cn
RDAP server
https://rdap.verisign.com/com/v1/

Checks

  • i
    .com is a generic TLD (gTLD)
    Generic TLD under an ICANN registry agreement: ICANN-accredited registrars, UDRP and RDAP apply.
    #1
  • ✓ TLD delegated and signed #2
    .com is delegated in the root zone and DNSSEC-signed.
  • ✓ Expires on 2027-04-13 #3
    The registration is valid until 2027-04-13 (172 days).
  • i
    No transfer lock
    The domain has no transfer lock (status: active). A registrar lock protects against unauthorized transfers.
    #4
  • ✓ Registry and delegation match #5
    The nameservers registered at the registry are the ones published in DNS.

Delegation

info

ns1.dns.com.cn, ns2.dns.com.cn

Found

Parent zone
com
Delegation from
a.gtld-servers.net (192.5.6.30)
NS at the parent
ns1.dns.com.cn, ns2.dns.com.cn
NS in the zone
ns1.dns.com.cn, ns2.dns.com.cn
NameserverAddressesNetwork (AS)Glue
ns1.dns.com.cn61.240.129.114 61.172.183.70 240c:4082:ffff:ff01:0:d:0:34aAS4837 CHINA169-Backbone - CHINA UNICOM China169 Backbone, CN AS4811 CHINANET-SHANGHAI-MAN - China Telecom (Group), CN AS38365 Baidu - Beijing Baidu Netcom Science and Technology Co., Ltd., CN-
ns2.dns.com.cn61.172.183.76 61.240.129.147 240c:4082:ffff:ff01:0:d:0:69AS4811 CHINANET-SHANGHAI-MAN - China Telecom (Group), CN AS4837 CHINA169-Backbone - CHINA UNICOM China169 Backbone, CN AS38365 Baidu - Beijing Baidu Netcom Science and Technology Co., Ltd., CN-

Checks

  • i
    2 nameservers
    Two nameservers meet the minimum; RFC 2182 recommends three or more for important zones: ns1.dns.com.cn, ns2.dns.com.cn.
    #6
  • ✓ Parent and zone agree #7
    The parent delegation and the zone's NS records list the same nameservers.
  • ✓ No glue needed #8
    All nameservers are outside the zone, so no glue records are needed.
  • ✓ 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 240c:4082:ffff::/48, while the other address family is spread over several networks.
    #10
  • ✓ 3 autonomous systems #11
    The nameservers are spread over: AS38365 (Baidu - Beijing Baidu Netcom Science and Technology Co., Ltd., CN): 2 addresses; AS4811 (CHINANET-SHANGHAI-MAN - China Telecom (Group), CN): 2 addresses; AS4837 (CHINA169-Backbone - CHINA UNICOM China169 Backbone, CN): 2 addresses.
  • i
    All nameserver names under .cn
    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.

Nameservers

fail

5 of 6 addresses answer authoritatively

Found

NameserverAnswerRecursionTCP / EDNSAXFRVersion
ns1.dns.com.cn 61.240.129.114NOERROR, 236 ms, authoritativenono / yesrefused9.11.0pre-alpha
ns1.dns.com.cn 61.172.183.70NOERROR, 192 ms, authoritativenono / norefused9.11.0pre-alpha
ns1.dns.com.cn 240c:4082:ffff:ff01:0:d:0:34ano responsenono / no--
ns2.dns.com.cn 61.172.183.76NOERROR, 424 ms, authoritativenono / norefused9.11.0pre-alpha
ns2.dns.com.cn 61.240.129.147NOERROR, 185 ms, authoritativenono / yesrefused9.11.0pre-alpha
ns2.dns.com.cn 240c:4082:ffff:ff01:0:d:0:69NOERROR, 252 ms, authoritativenono / yesrefused9.11.0pre-alpha

Checks

  • ✗
    Nameservers not responding
    These addresses did not answer, so resolvers waste time on timeouts: ns1.dns.com.cn (240c:4082:ffff:ff01:0:d:0:34a): read udp [2a01:4f8:1c1c:eebf::1]:42628->[240c:4082:ffff:ff01:0:d:0:34a]:53: i/o timeout.
    #14
  • ✓ 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: ns1.dns.com.cn: "9.11.0pre-alpha"; ns2.dns.com.cn: "9.11.0pre-alpha". Hide or replace the version string.
    #17
  • ✓ Zone transfers refused #18
    No nameserver allows a zone transfer to the public.
  • ✗
    No DNS over TCP
    DNS over TCP is required (RFC 7766); without it, large answers such as DNSSEC responses fail. Not answering over TCP: ns1.dns.com.cn (61.240.129.114): dial tcp 61.240.129.114:53: i/o timeout; ns1.dns.com.cn (61.172.183.70): dial tcp 61.172.183.70:53: i/o timeout; ns2.dns.com.cn (61.172.183.76): dial tcp 61.172.183.76:53: i/o timeout; ns2.dns.com.cn (61.240.129.147): dial tcp 61.240.129.147:53: i/o timeout; ns2.dns.com.cn (240c:4082:ffff:ff01:0:d:0:69): dial tcp [240c:4082:ffff:ff01:0:d:0:69]:53: i/o timeout.
    #19
  • !
    No EDNS
    These nameservers don't support EDNS(0), needed for DNSSEC and answers larger than 512 bytes: ns1.dns.com.cn (61.172.183.70), ns2.dns.com.cn (61.172.183.76).
    #20
  • ✓ Public addresses #21
    All nameserver addresses are publicly routable.

SOA

warn

serial 56 · primary dns.bizcn.com

Found

Primary (MNAME)
dns.bizcn.com
Contact (RNAME)
abuse.bizcn.com
Serial
56
Refresh / retry
28800 s / 14400 s
Expire
14400 s
Negative TTL
600 s

Serial per nameserver

NameserverSerial
ns1.dns.com.cn (61.240.129.114)56
ns1.dns.com.cn (61.172.183.70)56
ns2.dns.com.cn (61.172.183.76)56
ns2.dns.com.cn (61.240.129.147)56
ns2.dns.com.cn (240c:4082:ffff:ff01:0:d:0:69)56

Checks

  • ✓ Serial 56 everywhere #22
    All nameservers serve the same version of the zone.
  • !
    Unusual SOA timers
    expire 4h is shorter than 7d; secondaries stop answering too soon when the primary is down; expire 4h must be longer than refresh + retry. Current values: refresh 8h, retry 4h, expire 4h, negative TTL 10m.
    #23
  • i
    Hidden master
    The primary nameserver dns.bizcn.com is not listed as a nameserver: a hidden master that only feeds the public secondaries. That is a common setup; make sure it is not reachable for zone transfers from outside.
    #24
  • ✓ Contact abuse@bizcn.com #25
    The SOA RNAME abuse.bizcn.com means abuse@bizcn.com.
  • ✓ Counter serial #26
    The serial 56 is a plain counter.

DNSSEC

warn

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

Records

warn

7 records at the apex

Found

Read from
61.240.129.114:53
TypeValueTTL
SOAdns.bizcn.com. abuse.bizcn.com. 56 28800 14400 14400 600600
NSns1.dns.com.cn.600
NSns2.dns.com.cn.600
A47.92.89.13120
MX5 mx1.qiye.aliyun.com.120
MX10 mx2.qiye.aliyun.com.120
MX15 mx3.qiye.aliyun.com.120

Checks

  • !
    Very low TTLs
    These records have a TTL below 5m, causing extra queries and slower lookups: A (2m), MX (2m). Low TTLs are useful just before a planned change. The NS TTL at the parent is 2d and in the zone 10m; resolvers may use either.
    #32
  • ✓ No CNAME at the apex #33
    The zone apex has no CNAME record.
  • ✓ No wildcard #34
    Names that don't exist return NXDOMAIN.
  • i
    No CAA records
    Without CAA records any certificate authority may issue certificates for this domain. A CAA record limits issuance to the CAs you use.
    #35