grena.cz

.cz dns crawl

First seen 2026-05-31 · Last seen 2026-06-02 · ok HTTP/1.1 200 551 ms crawled 2026-05-31

CZ · 193.105.159.70 · AS24806 INTERNET CZ, a.s.

Reputation 89/100 weak security headers dmarc monitor-only

Classifying

HTML metadata

Title: Izolační a protipožární desky, žáruvzdorné materiály | GRENA.cz
Description: Dodáváme Izolační vermikulitové desky, žáruvzdorné, nehořlavé a protipožární materiály.
Language: cs-CZ

Technology

Server: Microsoft-IIS
ASP.NET: 4.0.30319

Analytics

Google Tag Manager

Third-party hosts loaded (1)

www.googletagmanager.com×1

Social

Contact

Email

grena@grena.cz

Phone

+420381549111

DNS records live

NS

ns.forpsi.cz
ns.forpsi.it
ns.forpsi.net

MX

10 mail.grena.cz
20 server.trefcon.cz

Verified for

Microsoft 365

Email authentication partial

SPF

v=spf1 ip4:89.221.222.57 ip6:2a02:2b88:2:b39::1 ip4:77.48.12.18 ip4:89.185.255.196 ip4:45.129.105.18 ip4:88.146.131.144/29 ip4:78.24.14.0/24 ip4:217.16.184.0/24 ip4:78.24.14.20 ip4:78.24.14.65 ip4:78.24.14.91 ip4:78.24.14.210 ip4:78.24.14.225 ip4:217.16.184.126 ip4:217.16.184.22 ip4:185.183.8.171 ip4:217.16.187.41 ip4:217.16.187.42 ip4:217.16.187.43 ip4:217.16.187.44 ip4:217.16.187.45 ip4:62.109.154.15 ip6:2a01:5e0:4b::/48 include:servers.mcsv.net include:_spf.savana.cz -all

strict (-all)

DMARC

v=DMARC1; p=none; rua=mailto:dmarc-reports@grena.cz; ruf=mailto:dmarc-reports@grena.cz; fo=1; aspf=s; adkim=s; pct=100

policy: none (monitoring only)

DKIM

k1: k=rsa; p=MIGfMA0GCSqGSIb3DQEBAQUAA4GNADCBiQKBgQDbNrX2cY/GUKIFx2G/1I00ftdAj713WP9AQ1xir85i89sA2guU0ta4UX1Xzm06XIU6iBP41VwmPwBGRNofhBVR+e6WHUo…

selectors probed

Certificate (current)

R13

from 2026-04-04 to 2026-07-03

Expires in 30 days

Full certificate history on crt.sh ↗

HTTP security headers

Header hygiene 30/100 Checked live page: https://grena.cz/

findings

missing HSTS
missing Content Security Policy
missing frame protection
missing content type protection
missing Referrer Policy
missing Permissions Policy