1und1.de

Readiness by lane

Green: 1und1.de. Thin bar: Telecommunications & Internet peer median.

Priority fixes for 1und1.de

Ordered by impact and by how common each practice is among peers.

1. Priority 1 · Harden

   HSTS kept for at least a year

   Observed: Strict-Transport-Security was sent with a max-age of 180 days, below the one-year benchmark.

   Why it matters: HSTS tells browsers to use HTTPS for your host on every later visit, which removes the window where a first HTTP request can be intercepted.

   What to do: Send Strict-Transport-Security on HTTPS responses. Start with a short max-age (for example 300 seconds), confirm every subdomain works over HTTPS, then raise it in steps to 31536000. Add includeSubDomains only when all subdomains are HTTPS. HSTS preload is optional and hard to undo; hstspreload.org itself does not recommend it by default.

   On Cloudflare: Enable HSTS under SSL/TLS > Edge Certificates > HTTP Strict Transport Security and raise max-age gradually.

   54% of Telecommunications & Internet peers do this. Limit: Read from the homepage response only; other pages or regions may send different headers.

   Guide: HTTPS and TLS Guide for Website Owners

2. Priority 2 · Accelerate

   Static files cached for 30 days or more

   Observed: A same-site stylesheet or script was cacheable for no max-age, short of the 30-day benchmark.

   What to do: Give versioned (fingerprinted) CSS, JavaScript, fonts and images Cache-Control: public, max-age=31536000, immutable, and change the file name whenever the content changes.

   On Cloudflare: Use Cache Rules to set edge and browser TTLs for static file paths.

   41% of Telecommunications & Internet peers do this.

   Guide: Browser Caching Guide for Website Owners

3. Priority 3 · Enable

   Social preview image set

   Observed: The homepage had no og:image, so shared links may show without a preview image.

   What to do: Add Open Graph tags, including og:image with a 1200 x 630 image.

   59% of Telecommunications & Internet peers do this.

   Guide: SEO Checklist for a New Website

4. Priority 4 · Harden

   CAA records limit who can issue certificates

   Observed: No CAA record was found for 1und1.de, so any public certificate authority may issue for it.

   What to do: Publish CAA records naming every CA you actually use, including the CAs your CDN uses for managed certificates. Add an iodef contact if you want reports.

   On Cloudflare: Cloudflare documents which CAs its managed certificates need; include them in your CAA records.

   15% of Telecommunications & Internet peers do this.

   Guide: HTTPS and TLS Guide for Website Owners

What 1und1.de already does well

Practices fewer than half of Telecommunications & Internet peers use.

• security.txt publishedsecurity.txt with a contact found.13% of peers
• Certificate lifetime of 100 days or lessShort-lived 90-day certificate from Google Trust Services, already inside the 2027 limit.28% of peers
• Reachable over IPv6IPv6 address published.33% of peers

What we saw

Homepage checked

https://www.1und1.de/

Homepage response

HTTP 200

TLS

TLSv1.3, HTTP/2

Certificate

Google Trust Services, 90-day validity, expiring 2027-01-15

CDN or edge

Cloudflare

DNS operators

IONOS DNS

HSTS

max-age 180 days, includeSubDomains

DMARC policy

p=quarantine

Homepage HTML

356 KB, gzip

Images on homepage

149 (webp 256, svg 189, png 70, jpg 67)

Limits: homepage only, one location, one moment. Header checks reflect the homepage response; other pages may differ.

Stack and providers

Seen in the homepage response, certificate and DNS. Provider pages compare how their customers configure the same checks.

All 31 checks

Select a gap for the method and fix. How each check works

Compare with other Telecommunications & Internet sites

• datamartgh.shop80
• elisa.fi80
• kpn.com82
• telia.se82
• vodafone.ro81

Telecommunications & Internet readiness benchmark