linuxdays.org - dns.ninja

`linuxdays.org`

DNSSEC	🔒 Signed (DS record present)
A	2a03:3b40:fe:39b::1^{🇨🇿 MASTER-AS2a03:3b40::/40 VPSFREE-IPV6-PRG2}
		PTR	`www.linuxdays.cz`
A	37.205.10.200^{🇨🇿 MASTER-AS37.205.8.0/22 RELBIT-VPSFREE}
NS	`ns1.petrkrcmar.cz` ⭐ ⚠️ Not in parent delegation
		A	2a03:3b40:fe:50d::1^{🇨🇿 MASTER-AS2a03:3b40::/40 VPSFREE-IPV6-PRG2}
			PTR	`vf.krcmarovi.cz`
		A	37.205.10.41^{🇨🇿 MASTER-AS37.205.8.0/22 RELBIT-VPSFREE}
			PTR	`vf.krcmarovi.cz`
NS	`flexi.oskarcz.net`
		A	2001:1528:132:70::1^{🇨🇿 CASABLANCA-AS2001:1528::/32 Casablanca INT v6 network}
			PTR	`flexi.oskarcz.net`
		A	85.239.227.179^{🇨🇿 CASABLANCA-AS85.239.227.0/24 Casablanca INT}
			PTR	`flexi.oskarcz.net`
NS	`ns2.petrkrcmar.cz` ⚠️ Not in parent delegation
		A	2a03:3b40:100::1:534^{🇨🇿 MASTER-AS2a03:3b40:100::/40 VPSFREE-IPV6-BRQ2}
			PTR	`ns2.petrkrcmar.cz`
		A	185.8.166.132^{🇨🇿 MASTER-AS185.8.166.0/23 VPSFREE-BRQ4}
			PTR	`ns2.petrkrcmar.cz`
NS	`vf.krcmarovi.cz` ⚠️ Not in zone NS records
		A	2a03:3b40:fe:50d::1^{🇨🇿 MASTER-AS2a03:3b40::/40 VPSFREE-IPV6-PRG2}
			PTR	`vf.krcmarovi.cz`
		A	37.205.10.41^{🇨🇿 MASTER-AS37.205.8.0/22 RELBIT-VPSFREE}
			PTR	`vf.krcmarovi.cz`
NS	`vm.krcmarovi.cz` ⚠️ Not in zone NS records
MX	`ag1.cesnet.cz` ⭐
		A	2001:718:ff05:208::94^{🇨🇿 CESNET2001:718::/32 6-TCZ}
			PTR	`ag1.cesnet.cz`
		A	78.128.247.94^{🇨🇿 CESNET78.128.128.0/17 -TCZ}
			PTR	`ag1.cesnet.cz`
MX	`ag2.cesnet.cz` ⭐
		A	2001:718:ff05:10b::245^{🇨🇿 CESNET2001:718::/32 6-TCZ}
			PTR	`ag2.cesnet.cz`
		A	78.128.248.245^{🇨🇿 CESNET78.128.128.0/17 -TCZ}
			PTR	`ag2.cesnet.cz`
TXT	`v=spf1 a:www.linuxdays.cz ~all`
SOA	`ns1.petrkrcmar.cz`root@petrkrcmar.cz 2025-07-22 #12

`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=1783460849

Same first word

linuxdays.cz

linuxdays.ch

linuxdays.lu

linuxdays.ru

linuxdays.eu

linuxdays.org

linuxdays.pl

linuxdays.at

DNS History

16 records (9 active, 7 former)

●NSflexi.oskarcz.net2016-03-28 → 2026-07-07 · 3 obs

○ 2015-11-02 10:56:06
● 2016-03-28 05:21:08
● 2026-07-07 22:15:18

○NSns.web4u.cz2015-06-10 → 2015-11-02 · 4 obs

● 2015-06-10 07:50:50
● 2015-11-02 10:56:06
○ 2016-03-28 05:21:08
○ 2026-07-07 22:15:18

●NSns1.petrkrcmar.cz2026-03-11 → 2026-07-07 · 3 obs

○ 2016-03-28 05:21:08
● 2026-03-11 15:18:38
● 2026-07-07 22:15:18

●NSns2.petrkrcmar.cz2026-03-11 → 2026-07-07 · 3 obs

○ 2016-03-28 05:21:08
● 2026-03-11 15:18:38
● 2026-07-07 22:15:18

○NSns2.web4u.cz2015-06-10 → 2015-11-02 · 4 obs

● 2015-06-10 07:50:50
● 2015-11-02 10:56:06
○ 2016-03-28 05:21:08
○ 2026-07-07 22:15:18

●NSvf.krcmarovi.cz2016-03-28 → 2026-07-07 · 3 obs

○ 2015-11-02 10:56:06
● 2016-03-28 05:21:08
● 2026-07-07 22:15:18

●NSvm.krcmarovi.cz2016-03-28 → 2026-07-07 · 3 obs

○ 2015-11-02 10:56:06
● 2016-03-28 05:21:08
● 2026-07-07 22:15:18

●MXag1.cesnet.cz2026-03-11 → 2026-07-07 · 3 obs

○ 2018-06-29 01:07:14
● 2026-03-11 15:18:38
● 2026-07-07 22:15:18

●MXag2.cesnet.cz2026-03-11 → 2026-07-07 · 3 obs

○ 2018-06-29 01:07:14
● 2026-03-11 15:18:38
● 2026-07-07 22:15:18

○MXmx.cesnet.cz2015-11-02 → 2018-06-29 · 4 obs

● 2015-11-02 10:56:06
● 2018-06-29 01:07:14
○ 2026-03-11 15:18:38
○ 2026-07-07 22:15:18

○MXmx2.cesnet.cz2015-11-02 → 2018-06-29 · 4 obs

● 2015-11-02 10:56:06
● 2018-06-29 01:07:14
○ 2026-03-11 15:18:38
○ 2026-07-07 22:15:18

○A178.238.42.572015-11-02 → 2015-11-02 · 4 obs

○ 2015-06-10 07:50:50
● 2015-11-02 10:56:06
○ 2016-03-28 05:21:08
○ 2026-07-07 22:15:18

○A2a01:430:17:1::ffff:6132016-03-28 → 2018-06-29 · 5 obs

○ 2015-11-02 10:56:06
● 2016-03-28 05:21:08
● 2018-06-29 01:07:14
○ 2026-03-11 15:18:38
○ 2026-07-07 22:15:18

●A2a03:3b40:fe:39b::12026-03-11 → 2026-07-07 · 3 obs

○ 2018-06-29 01:07:14
● 2026-03-11 15:18:38
● 2026-07-07 22:15:18

●A37.205.10.2002016-03-28 → 2026-07-07 · 3 obs

○ 2015-11-02 10:56:06
● 2016-03-28 05:21:08
● 2026-07-07 22:15:18

○A80.79.27.592015-06-10 → 2015-06-10 · 3 obs

● 2015-06-10 07:50:50
○ 2015-11-02 10:56:06
○ 2026-07-07 22:15:18

🔍 DNS Trace

📋 Delegation Chain

Zone	Nameservers	Glue
org	b0.org.afilias-nst.org, b2.org.afilias-nst.org, d0.org.afilias-nst.org	-
linuxdays.org	vf.krcmarovi.cz, vm.krcmarovi.cz, flexi.oskarcz.net	-

✅ Authoritative Response

Server:85.239.227.179

NS records: vf.krcmarovi.cz, vm.krcmarovi.cz, flexi.oskarcz.net

🔒 DNSSEC Status

🔐 Secure (DNSSEC validated)

Chain of trust verified from root to domain

⏱️ Timing

Total: 2655ms | Queries: -

📄 Records

Type	Count	Sample Data
A	1	`37.205.10.200`
AAAA	1	`2a03:3b40:fe:39b::1`
NS	3	`ns1.petrkrcmar.cz, ns2.petrkrcmar.cz...`
MX	2	`ag1.cesnet.cz (pri: 10), ag2.cesnet.cz (pri: 10)`
TXT	1	`v=spf1 a:www.linuxdays.cz ~all`
SOA	1	`ns1.petrkrcmar.cz root.petrkrcmar.cz`

Analysis

IP Addresses

linuxdays.org resolves to the IP addresses 37.205.10.200 and 2a03:3b40:fe:39b::1

linuxday.cz, linuxdays.eu, www.linuxdays.cz and linuxdays.cz are examples of host names that share IP numbers with linuxdays.org.

Name Servers

linuxdays.org delegates to five name servers: vf.krcmarovi.cz, vm.krcmarovi.cz, ns1.petrkrcmar.cz and two others.

linuxdays.org shares at least some of its name servers with other domains, including 0.7.0.0.2.3.1.0.8.2.5.1.1.0.0.2.ip6.arpa, caletka.cz, krcmarovi.cz and two others.

These name servers are frequently paired with the name servers flexi.oskarcz.net, ns2.petrkrcmar.cz and auron.oskarcz.eu.

vf.krcmarovi.cz, ns1.petrkrcmar.cz, ns2.petrkrcmar.cz and flexi.oskarcz.net each resolve to two IP addresses. vf.krcmarovi.cz points to 37.205.10.41 and 2a03:3b40:fe:50d::1. ns1.petrkrcmar.cz points to 37.205.10.41 and 2a03:3b40:fe:50d::1. ns2.petrkrcmar.cz points to 185.8.166.132 and 2a03:3b40:100::1:534. flexi.oskarcz.net points to 85.239.227.179 and 2001:1528:132:70::1.

vf.krcmarovi.cz along with ns1.petrkrcmar.cz each resolve to 2a03:3b40:fe:50d::1 IP addresses.

vf.krcmarovi.cz along with ns1.petrkrcmar.cz each resolve to 37.205.10.41 IP addresses.

Mail Servers

linuxdays.org is served by two mail servers, ag1.cesnet.cz and ag2.cesnet.cz.

Among the domains sharing a mail server setup with linuxdays.org are amapa.cz, vspj.cz, uk-simple.cuni.cz and two others.

There is at least a partial MX overlap between linuxdays.org and other domains, including brana.mustribro.cz, ddm.nmnm.cz, thsbp.cas.cz and two others.

These mail servers often co-occur with the mail servers mail.mustribro.cz.

ag1.cesnet.cz and ag2.cesnet.cz both carry two IP addresses. The A records for ag1.cesnet.cz are 78.128.247.94 and 2001:718:ff05:208::94; the A records for ag2.cesnet.cz are 78.128.248.245 and 2001:718:ff05:10b::245.