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Dnssecmagic.js

Minimal HTML/JavaScript/jQuery code to determine if Web-browser is using a DNSSEC-validating cache

Install / Use

/learn @jpmens/Dnssecmagic.js
About this skill

Quality Score

0/100

Supported Platforms

Universal

README

dnssecmagic.js

More

See my blog post for full details.

Bogus ^W Modus operandi

Your page (see index.html below) sets a 3000ms timer and tries to load a 1x1-pixel graphic from dnssec-failed.org. If that file can be loaded, the timer is stopped, and we consider you're using a non-DNSSEC-validating cache because your browser loaded the image, so we know it was able to resolve www.dnssec-failed.org to an address record, and connected to the site.

If your browser is speaking to a validating cache, the cache will determine that the DNSSEC-signed zone www.dnssec-failed.org is bogus and will SERVFAIL; it will not return the address of the site. When the timer expires, we know (or hope?) DNSSEC is in use and can react accordingly.

The files

index.html

The file index.html contains snippets of code you copy/paste into your own project. That includes loading the two Javascript files and launching the startTimer() function.

dnssecmagic.js

Contains supporting routines needed to test whether the 1x1-pixel image was loaded, and populate the #dnssecmagic span. Change text and colours to suit yourself. The function you'll want to adapt is called showdnssecmagic(). It gets a True/False parameter depending on whether DNSSEC was detected or not.

Bugs

Yes.

I'm neither a designer, nor am I a Web developer. Fix things and send me pull-requests. Please.

Credits

View on GitHub
GitHub Stars8
CategoryDevelopment
Updated6mo ago
Forks0

Languages

JavaScript

Security Score

62/100

Audited on Oct 3, 2025

No findings