DNS lookup

Everything DNS says about a domain: traced from the root servers down, every record type asked of the domain's own nameservers, each nameserver checked, then every hostname and policy record it points at followed, with SPF, DMARC, DKIM and DNSSEC checked along the way.

205.251.192.101

101.192.251.205.in-addr.arpa

Zone 192.251.205.in-addr.arpa129 queries in 0.6 s2026-11-09 05:55:08 UTCNot DNSSEC-signed

WHOIS for 205.251.192.101 →Text JSON

Warning Nameservers disagree on the SOA serial (1 on ns-1496.awsdns-59.org, ns-1804.awsdns-33.co.uk, ns-236.awsdns-29.com, ns-554.awsdns-05.net; 4 on pdns1.ultradns.net, x1.amazonaws.com, x2.amazonaws.com, x3.amazonaws.org, x4.amazonaws.org). Normal when two DNS providers serve the zone, each numbering its own copy; otherwise some servers haven't picked up the latest change.
Warning The parent zone delegates to pdns1.ultradns.net, x1.amazonaws.com, x2.amazonaws.com, x3.amazonaws.org, x4.amazonaws.org but 192.251.205.in-addr.arpa itself lists ns-1496.awsdns-59.org, ns-1804.awsdns-33.co.uk, ns-236.awsdns-29.com, ns-554.awsdns-05.net. Make the two lists match.
Note 192.251.205.in-addr.arpa isn't signed with DNSSEC, so resolvers can't tell forged answers from real ones.

Records

Asked directly of ns-1496.awsdns-59.org (205.251.197.216), an authoritative server: no cache in between, so these are the live values.

PTR Reverse pointer

172800

PTR

ns-101.awsdns-12.com.

ANY query: 1 records

172800

PTR

ns-101.awsdns-12.com.

No records of type A, AAAA, CNAME, DNAME, NS, SOA, MX, TXT, CAA, HTTPS, SVCB, SRV, NAPTR, DS, DNSKEY, CDS, CDNSKEY, NSEC3PARAM, TLSA, SSHFP, LOC, HINFO, RP, URI, SPF, OPENPGPKEY, ZONEMD, CSYNC.

Resolution trace

.asked j.root-servers.net 192.58.128.3039 ms
Referral to in-addr.arpa. signed (4 DS)
- a.in-addr-servers.arpa 199.180.182.53 2620:37:e000::53
- b.in-addr-servers.arpa 199.253.183.183 2001:500:87::87
- c.in-addr-servers.arpa 196.216.169.10 2001:43f8:110::10
- d.in-addr-servers.arpa 200.10.60.53 2001:13c7:7010::53
- e.in-addr-servers.arpa 203.119.86.101 2001:dd8:6::101
- f.in-addr-servers.arpa 193.0.9.1 2a13:27c0:30::1
192.33.4.12 failed: NOERROR
in-addr.arpa.asked f.in-addr-servers.arpa 193.0.9.111 ms
Referral to 205.in-addr.arpa. signed (1 DS)
- r.arin.net 199.180.180.63 2001:500:f0::63
- u.arin.net 204.61.216.50 2001:500:14:6050:ad::1
- x.arin.net 199.180.180.63 2001:500:f0::63
- y.arin.net 192.82.134.30 2001:500:127::30
- z.arin.net 199.180.180.63 2001:500:f0::63
- arin.authdns.ripe.net 193.0.9.10 2a13:27c0:30::10
No glue for r.arin.net, u.arin.net, x.arin.net, y.arin.net, z.arin.net, arin.authdns.ripe.net: addresses looked up via a resolver.
200.10.60.53 failed: NOERROR
205.in-addr.arpa.asked y.arin.net 192.82.134.306.2 ms
Referral to 192.251.205.in-addr.arpa. unsigned delegation
- x1.amazonaws.com 156.154.64.10
- x3.amazonaws.org 156.154.150.1
- pdns1.ultradns.net 204.74.108.1 2001:502:f3ff::1
- x2.amazonaws.com 156.154.65.10
- x4.amazonaws.org 204.74.120.1
No glue for x1.amazonaws.com, x3.amazonaws.org, pdns1.ultradns.net, x2.amazonaws.com, x4.amazonaws.org: addresses looked up via a resolver.
199.180.180.63 failed: NOERROR
192.251.205.in-addr.arpa.asked pdns1.ultradns.net 204.74.108.15.4 ms
Answer (authoritative):
101.192.251.205.in-addr.arpa. 172800 PTR ns-101.awsdns-12.com.

Nameservers

Every address of every nameserver, asked for 192.251.205.in-addr.arpa's SOA. "Parent" means the 205.in-addr.arpa zone delegates to it; "zone" means 192.251.205.in-addr.arpa lists it itself.

Nameserver

Listed in

Address

Status

Serial

Time

ns-1496.awsdns-59.org

zone

205.251.197.216

authoritative

5.5 ms

2600:9000:5305:d800::1

authoritative

5.6 ms

ns-1804.awsdns-33.co.uk

zone

205.251.199.12

authoritative

11 ms

2600:9000:5307:c00::1

authoritative

11 ms

ns-236.awsdns-29.com

zone

205.251.192.236

authoritative

11 ms

2600:9000:5300:ec00::1

authoritative

11 ms

ns-554.awsdns-05.net

zone

205.251.194.42

authoritative

7.2 ms

2600:9000:5302:2a00::1

authoritative

7.5 ms

pdns1.ultradns.net

parent

204.74.108.1 glue

authoritative

6.5 ms

2001:502:f3ff::1 glue

authoritative

7.0 ms

x1.amazonaws.com

parent

156.154.64.10 glue

authoritative

6.4 ms

x2.amazonaws.com

parent

156.154.65.10 glue

authoritative

6.5 ms

x3.amazonaws.org

parent

156.154.150.1 glue

authoritative

7.2 ms

x4.amazonaws.org

parent

204.74.120.1 glue

authoritative

17 ms

DNSSEC

192.251.205.in-addr.arpa isn't signed: no DS at the parent and no DNSKEY in the zone.

Hosts and reverse DNS

Every hostname the records point at, resolved to its addresses; each address's PTR (reverse DNS), with ✓ where the PTR name resolves back to the same address.

Host

Address

Reverse DNS (PTR)

ns-1496.awsdns-59.org

nameserver

205.251.197.216

ns-1496.awsdns-59.org ✓

2600:9000:5305:d800::1

ns-1496.awsdns-59.org ✓

ns-1804.awsdns-33.co.uk

nameserver

205.251.199.12

ns-1804.awsdns-33.co.uk ✓

2600:9000:5307:c00::1

ns-1804.awsdns-33.co.uk ✓

ns-236.awsdns-29.com

nameserver

205.251.192.236

ns-236.awsdns-29.com ✓

2600:9000:5300:ec00::1

ns-236.awsdns-29.com ✓

ns-554.awsdns-05.net

nameserver

205.251.194.42

ns-554.awsdns-05.net ✓

2600:9000:5302:2a00::1

ns-554.awsdns-05.net ✓

pdns1.ultradns.net

nameserver

204.74.108.1

pdns1.ultradns.net ✓

2001:502:f3ff::1

pdns1.ultradns.net ✓

x1.amazonaws.com

nameserver

156.154.64.10

u1.amazonaws.com ✓

x2.amazonaws.com

nameserver

156.154.65.10

u2.amazonaws.com ✓

x3.amazonaws.org

nameserver

156.154.150.1

dns-01.ultradns2.com ✓

x4.amazonaws.org

nameserver

204.74.120.1

dns-01.ultradns2.org ✓

ns-101.awsdns-12.com

PTR target

205.251.192.101

ns-101.awsdns-12.com ✓

2600:9000:5300:6500::1

ns-101.awsdns-12.com ✓

Public resolvers

What four public resolvers answer right now, from their caches. Highlighted values differ from the authoritative answer: either a recent change they haven't picked up yet (the TTL says how long until they do), or, for A and AAAA, a CDN or geo-routed site handing each resolver location its own addresses.

Resolver

PTR

Cloudflare 1.1.1.1

ns-101.awsdns-12.com.

TTL 172800

Google 8.8.8.8

ns-101.awsdns-12.com.

TTL 21600

Quad9 9.9.9.9

ns-101.awsdns-12.com.

TTL 43200

OpenDNS 208.67.222.222

ns-101.awsdns-12.com.

TTL 172800

Text dump

; DNS report for 101.192.251.205.in-addr.arpa (205.251.192.101)
; 2026-11-09 05:55:08 UTC, 129 queries in 0.57 s, zone 192.251.205.in-addr.arpa

;; FINDINGS
;  [WARN] Nameservers disagree on the SOA serial (1 on ns-1496.awsdns-59.org, ns-1804.awsdns-33.co.uk, ns-236.awsdns-29.com, ns-554.awsdns-05.net; 4 on pdns1.ultradns.net, x1.amazonaws.com, x2.amazonaws.com, x3.amazonaws.org, x4.amazonaws.org). Normal when two DNS providers serve the zone, each numbering its own copy; otherwise some servers haven't picked up the latest change.
;  [WARN] The parent zone delegates to pdns1.ultradns.net, x1.amazonaws.com, x2.amazonaws.com, x3.amazonaws.org, x4.amazonaws.org but 192.251.205.in-addr.arpa itself lists ns-1496.awsdns-59.org, ns-1804.awsdns-33.co.uk, ns-236.awsdns-29.com, ns-554.awsdns-05.net. Make the two lists match.
;  [INFO] 192.251.205.in-addr.arpa isn't signed with DNSSEC, so resolvers can't tell forged answers from real ones.

;; RECORDS (authoritative, from ns-1496.awsdns-59.org (205.251.197.216))
101.192.251.205.in-addr.arpa.	172800	IN	PTR	ns-101.awsdns-12.com.

;; TRACE
;  101.192.251.205.in-addr.arpa PTR
;  . @j.root-servers.net (192.58.128.30) 39 ms [NOERROR qr]: referral to in-addr.arpa.
in-addr.arpa.		NS	a.in-addr-servers.arpa.	; 199.180.182.53 2620:37:e000::53
in-addr.arpa.		NS	b.in-addr-servers.arpa.	; 199.253.183.183 2001:500:87::87
in-addr.arpa.		NS	c.in-addr-servers.arpa.	; 196.216.169.10 2001:43f8:110::10
in-addr.arpa.		NS	d.in-addr-servers.arpa.	; 200.10.60.53 2001:13c7:7010::53
in-addr.arpa.		NS	e.in-addr-servers.arpa.	; 203.119.86.101 2001:dd8:6::101
in-addr.arpa.		NS	f.in-addr-servers.arpa.	; 193.0.9.1 2a13:27c0:30::1
in-addr.arpa.	86400	IN	DS	47054 8 2 5CAFCCEC201D1933B4C9F6A9C8F51E51F3B39979058AC21B8DF1B1F281CBC6F2
in-addr.arpa.	86400	IN	DS	53696 8 2 13E5501C56B20394DA921B51412D48B7089C5EB6957A7C58553C4D4D424F04DF
in-addr.arpa.	86400	IN	DS	54956 8 2 E0E2BF5CFBD66572CA05EC18267D91509BA6A9405AF05C3FD4141DFA45200C08
in-addr.arpa.	86400	IN	DS	63982 8 2 AAF4FB5D213EF25AE44679032EBE3514C487D7ABD99D7F5FEC3383D030733C73
;  in-addr.arpa. @f.in-addr-servers.arpa (193.0.9.1) 11 ms [NOERROR qr]: referral to 205.in-addr.arpa.
205.in-addr.arpa.		NS	r.arin.net.	; 199.180.180.63 2001:500:f0::63
205.in-addr.arpa.		NS	u.arin.net.	; 204.61.216.50 2001:500:14:6050:ad::1
205.in-addr.arpa.		NS	x.arin.net.	; 199.180.180.63 2001:500:f0::63
205.in-addr.arpa.		NS	y.arin.net.	; 192.82.134.30 2001:500:127::30
205.in-addr.arpa.		NS	z.arin.net.	; 199.180.180.63 2001:500:f0::63
205.in-addr.arpa.		NS	arin.authdns.ripe.net.	; 193.0.9.10 2a13:27c0:30::10
205.in-addr.arpa.	86400	IN	DS	37219 8 2 8995F93F2EFA4E23997F6A7E3455F1E9A7C20A10A346FDF5A89AA1775664EFF9
;  205.in-addr.arpa. @y.arin.net (192.82.134.30) 6.2 ms [NOERROR qr]: referral to 192.251.205.in-addr.arpa.
192.251.205.in-addr.arpa.		NS	x1.amazonaws.com.	; 156.154.64.10
192.251.205.in-addr.arpa.		NS	x3.amazonaws.org.	; 156.154.150.1
192.251.205.in-addr.arpa.		NS	pdns1.ultradns.net.	; 204.74.108.1 2001:502:f3ff::1
192.251.205.in-addr.arpa.		NS	x2.amazonaws.com.	; 156.154.65.10
192.251.205.in-addr.arpa.		NS	x4.amazonaws.org.	; 204.74.120.1
;  192.251.205.in-addr.arpa. @pdns1.ultradns.net (204.74.108.1) 5.4 ms [NOERROR qr aa]: answer
101.192.251.205.in-addr.arpa.	172800	IN	PTR	ns-101.awsdns-12.com.

;; NAMESERVERS (SOA asked of each address)
;  ns-1496.awsdns-59.org [zone]
;    205.251.197.216                         ok                        1           5.5 ms
;    2600:9000:5305:d800::1                  ok                        1           5.6 ms
;  ns-1804.awsdns-33.co.uk [zone]
;    205.251.199.12                          ok                        1           11 ms
;    2600:9000:5307:c00::1                   ok                        1           11 ms
;  ns-236.awsdns-29.com [zone]
;    205.251.192.236                         ok                        1           11 ms
;    2600:9000:5300:ec00::1                  ok                        1           11 ms
;  ns-554.awsdns-05.net [zone]
;    205.251.194.42                          ok                        1           7.2 ms
;    2600:9000:5302:2a00::1                  ok                        1           7.5 ms
;  pdns1.ultradns.net [parent]
;    204.74.108.1                            ok                        4           6.5 ms
;    2001:502:f3ff::1                        ok                        4           7.0 ms
;  x1.amazonaws.com [parent]
;    156.154.64.10                           ok                        4           6.4 ms
;  x2.amazonaws.com [parent]
;    156.154.65.10                           ok                        4           6.5 ms
;  x3.amazonaws.org [parent]
;    156.154.150.1                           ok                        4           7.2 ms
;  x4.amazonaws.org [parent]
;    204.74.120.1                            ok                        4           17 ms

;; DNSSEC: unsigned

;; HOSTS
;  ns-1496.awsdns-59.org (nameserver)
;    205.251.197.216                         PTR ns-1496.awsdns-59.org (confirmed)
;    2600:9000:5305:d800::1                  PTR ns-1496.awsdns-59.org (confirmed)
;  ns-1804.awsdns-33.co.uk (nameserver)
;    205.251.199.12                          PTR ns-1804.awsdns-33.co.uk (confirmed)
;    2600:9000:5307:c00::1                   PTR ns-1804.awsdns-33.co.uk (confirmed)
;  ns-236.awsdns-29.com (nameserver)
;    205.251.192.236                         PTR ns-236.awsdns-29.com (confirmed)
;    2600:9000:5300:ec00::1                  PTR ns-236.awsdns-29.com (confirmed)
;  ns-554.awsdns-05.net (nameserver)
;    205.251.194.42                          PTR ns-554.awsdns-05.net (confirmed)
;    2600:9000:5302:2a00::1                  PTR ns-554.awsdns-05.net (confirmed)
;  pdns1.ultradns.net (nameserver)
;    204.74.108.1                            PTR pdns1.ultradns.net (confirmed)
;    2001:502:f3ff::1                        PTR pdns1.ultradns.net (confirmed)
;  x1.amazonaws.com (nameserver)
;    156.154.64.10                           PTR u1.amazonaws.com (confirmed)
;  x2.amazonaws.com (nameserver)
;    156.154.65.10                           PTR u2.amazonaws.com (confirmed)
;  x3.amazonaws.org (nameserver)
;    156.154.150.1                           PTR dns-01.ultradns2.com (confirmed)
;  x4.amazonaws.org (nameserver)
;    204.74.120.1                            PTR dns-01.ultradns2.org (confirmed)
;  ns-101.awsdns-12.com (PTR target)
;    205.251.192.101                         PTR ns-101.awsdns-12.com (confirmed)
;    2600:9000:5300:6500::1                  PTR ns-101.awsdns-12.com (confirmed)

;; PUBLIC RESOLVERS
;  Cloudflare PTR   ns-101.awsdns-12.com.  ttl 172800
;  Google     PTR   ns-101.awsdns-12.com.  ttl 21600
;  Quad9      PTR   ns-101.awsdns-12.com.  ttl 43200
;  OpenDNS    PTR   ns-101.awsdns-12.com.  ttl 172800