codeforces.org - dns.ninja

`codeforces.org`

DNSSEC	⚠️ Not signed
A	2606:4700:3030::ac43:83be^{🇺🇸 Cloudflare2606:4700:3030::/48 , Inc. 101 Townsend Street, San Francisco, California 94107, US} ✓ In HTTPS hints
A	2606:4700:3033::6815:afc^{🇺🇸 Cloudflare2606:4700:3033::/48 , Inc. 101 Townsend Street, San Francisco, California 94107, US} ✓ In HTTPS hints
A	104.21.10.252^{Cloudflare104.21.0.0/20 , Inc. 101 Townsend Street, San Francisco, California 94107, US} ✓ In HTTPS hints
A	172.67.131.190^{🇺🇸 Cloudflare172.67.128.0/20 , Inc. 101 Townsend Street, San Francisco, California 94107, US} ✓ In HTTPS hints
NS	`fred.ns.cloudflare.com` ⭐
		A	2606:4700:58::adf5:3b71^{🇺🇸 Cloudflare2606:4700:50::/44 , Inc. 101 Townsend Street, San Francisco, California 94107, US}
			PTR	`fred.ns.cloudflare.com`
		A	2803:f800:50::6ca2:c171^{🇨🇷 Cloudflare2803:f800:50::/45 LACNIC generated route6 for CloudFlare Latin America S.R.L}
			PTR	`fred.ns.cloudflare.com`
		A	2a06:98c1:50::ac40:2171^{🇺🇸 Cloudflare2a06:98c1:50::/45}
			PTR	`fred.ns.cloudflare.com`
		A	108.162.193.113^{🇺🇸 Cloudflare108.162.193.0/24 , Inc. 101 Townsend Street, San Francisco, California 94107, US}
			PTR	`fred.ns.cloudflare.com`
		A	172.64.33.113^{🇺🇸 Cloudflare172.64.33.0/24 , Inc. 101 Townsend Street, San Francisco, California 94107, US}
			PTR	`fred.ns.cloudflare.com`
		A	173.245.59.113^{🇺🇸 Cloudflare173.245.59.0/24 , Inc. 101 Townsend Street, San Francisco, California 94107, US}
			PTR	`fred.ns.cloudflare.com`
NS	`jean.ns.cloudflare.com`
		A	2606:4700:50::adf5:3a79^{🇺🇸 Cloudflare2606:4700:50::/44 , Inc. 101 Townsend Street, San Francisco, California 94107, US}
			PTR	`jean.ns.cloudflare.com`
		A	2803:f800:50::6ca2:c079^{🇨🇷 Cloudflare2803:f800:50::/45 LACNIC generated route6 for CloudFlare Latin America S.R.L}
			PTR	`jean.ns.cloudflare.com`
		A	2a06:98c1:50::ac40:2079^{🇺🇸 Cloudflare2a06:98c1:50::/45}
			PTR	`jean.ns.cloudflare.com`
		A	108.162.192.121^{🇺🇸 Cloudflare108.162.192.0/24 , Inc. 101 Townsend Street, San Francisco, California 94107, US}
			PTR	`jean.ns.cloudflare.com`
		A	172.64.32.121^{🇺🇸 Cloudflare172.64.32.0/24 , Inc. 101 Townsend Street, San Francisco, California 94107, US}
			PTR	`jean.ns.cloudflare.com`
		A	173.245.58.121^{🇺🇸 Cloudflare173.245.58.0/24 , Inc. 101 Townsend Street, San Francisco, California 94107, US}
			PTR	`jean.ns.cloudflare.com`
HTTPS	HTTP/2 ✓ hints match
		IPv4 hints	104.21.10.252, 172.67.131.190
		IPv6 hints	2606:4700:3030::ac43:83be, 2606:4700:3033::6815:afc
SOA	`fred.ns.cloudflare.com`dns@cloudflare.com serial=2408991392

`org`

	DNSSEC	🔒 Signed (DS record present)
	NS	`a0.org.afilias-nst.info` ⭐ ⚠️ Not in parent delegation
	NS	`a2.org.afilias-nst.info` ⚠️ Not in parent delegation
	NS	`b0.org.afilias-nst.org`
	NS	`b2.org.afilias-nst.org`
	NS	`c0.org.afilias-nst.info` ⚠️ Not in parent delegation
	NS	`d0.org.afilias-nst.org`
	SOA	`a0.org.afilias-nst.info`hostmaster@donuts.email serial=1784484933

Subdomains

userpic.codeforces.org

Same first word

codeforces.org

codeforces.ru

codeforces.me

codeforces.netlify.app

codeforces.com

codeforces.net

Similar names

codesforce.com

frescocode.com

codeforecs.s3-us-west-2.amazonaws.com

DNS History

15 records (6 active, 9 former)

○NSdns1.webdrive.ru2015-06-07 → 2016-09-23 · 4 obs

● 2015-06-07 09:08:10
● 2016-09-23 00:46:18
○ 2026-02-19 17:51:34
○ 2026-07-19 18:25:18

○NSdns2.webdrive.ru2015-06-07 → 2016-09-23 · 4 obs

● 2015-06-07 09:08:10
● 2016-09-23 00:46:18
○ 2026-02-19 17:51:34
○ 2026-07-19 18:25:18

●NSfred.ns.cloudflare.com2026-02-19 → 2026-07-19 · 3 obs

○ 2016-09-23 00:46:18
● 2026-02-19 17:51:34
● 2026-07-19 18:25:18

●NSjean.ns.cloudflare.com2026-02-19 → 2026-07-19 · 3 obs

○ 2016-09-23 00:46:18
● 2026-02-19 17:51:34
● 2026-07-19 18:25:18

●A104.21.10.2522026-02-19 → 2026-07-19 · 12 obs

○ 2016-09-23 00:46:18
● 2026-02-19 17:51:34
● 2026-02-21 19:59:52
○ 2026-02-22 08:57:28
● 2026-04-13 12:14:40
○ 2026-04-24 06:37:26
● 2026-04-26 07:38:04
● 2026-06-01 06:08:34
○ 2026-06-03 13:30:58
● 2026-06-07 23:19:04
○ 2026-07-14 12:46:48
● 2026-07-19 18:25:18

●A172.67.131.1902026-02-19 → 2026-07-19 · 12 obs

○A188.114.96.02026-02-22 → 2026-07-14 · 10 obs

○ 2026-02-21 19:59:52
● 2026-02-22 08:57:28
○ 2026-04-13 12:14:40
● 2026-04-24 06:37:26
○ 2026-04-26 07:38:04
○ 2026-06-01 06:08:34
● 2026-06-03 13:30:58
○ 2026-06-07 23:19:04
● 2026-07-14 12:46:48
○ 2026-07-19 18:25:18

○A188.114.97.02026-02-22 → 2026-07-14 · 10 obs

●A2606:4700:3030::ac43:83be2026-07-02 → 2026-07-19 · 4 obs

○ 2026-06-12 23:02:04
● 2026-07-02 03:54:54
○ 2026-07-14 12:46:48
● 2026-07-19 18:25:18

○A2606:4700:3031::ac43:83be2026-02-19 → 2026-06-12 · 13 obs

●A2606:4700:3033::6815:afc2026-07-02 → 2026-07-19 · 4 obs

○ 2026-06-12 23:02:04
● 2026-07-02 03:54:54
○ 2026-07-14 12:46:48
● 2026-07-19 18:25:18

○A2606:4700:3035::6815:afc2026-02-19 → 2026-06-12 · 13 obs

○A2a06:98c1:3120::2026-02-22 → 2026-07-14 · 10 obs

○A2a06:98c1:3121::2026-02-22 → 2026-07-14 · 10 obs

○A89.111.166.602015-06-07 → 2016-09-23 · 4 obs

● 2015-06-07 09:08:10
● 2016-09-23 00:46:18
○ 2026-02-19 17:51:34
○ 2026-07-19 18:25:18

🔍 DNS Trace

📋 Delegation Chain

Zone	Nameservers	Glue
org	b0.org.afilias-nst.org, b2.org.afilias-nst.org, d0.org.afilias-nst.org	-
codeforces.org	jean.ns.cloudflare.com, fred.ns.cloudflare.com	-

✅ Authoritative Response

Server:172.64.33.113

NS records: jean.ns.cloudflare.com, fred.ns.cloudflare.com

🔒 DNSSEC Status

⚠️ Insecure (no DNSSEC)

No DS record for codeforces.org (unsigned zone)

⏱️ Timing

Total: 842ms | Queries: -

📄 Records

Type	Count	Sample Data
A	2	`104.21.10.252, 172.67.131.190`
AAAA	2	`2606:4700:3033::6815:afc, 2606:4700:3030::ac43:83be`
NS	2	`fred.ns.cloudflare.com, jean.ns.cloudflare.com`
HTTPS	1	`{"priority":1,"target":".","alpn":["h2"]`
SOA	1	`fred.ns.cloudflare.com dns.cloudflare.co`

Analysis

Hierarchy

userpic.codeforces.org is a subdomain of codeforces.org.

IP Addresses

codeforces.org points to the four IP addresses 104.21.10.252, 172.67.131.190, 2606:4700:3030::ac43:83be and 2606:4700:3033::6815:afc.

Among the host names that share IP numbers with codeforces.org are gunzone.com, thelistservearchive.com, cpcontacts.shkodratravel.com and two others.

Name Servers

The NS records for codeforces.org delegate to fred.ns.cloudflare.com and jean.ns.cloudflare.com.

codeforces.org has the same name server delegation as a number of other domains, such as habcoprimatama.com, veganutmaningen.se, hallapproved.com and two more.

The name servers of codeforces.org overlap at least partially with those of other domains — among them disfuse.xyz, westerscheldevissen.nl, pfkotor.me and two more.

These name servers commonly appear in combination with the name servers fatima.ns.cloudflare.com.

Host names resolving to 6 IP numbers:

fred.ns.cloudflare.com maps to 108.162.193.113, 172.64.33.113, 173.245.59.113 and 3 additional IP addresses.

jean.ns.cloudflare.com maps to 108.162.192.121, 172.64.32.121, 173.245.58.121 and 3 additional IP addresses.