Verified Link

TwitterTwitter

Twitter Usage Statistics · Download List of All Websites using Twitter

The website mentions twitter.com in some form.

Email Hosting Providers

SPFSPF

SPF Usage Statistics · Download List of All Websites using SPF

The Sender Policy Framework is an open standard specifying a technical method to prevent sender address forgery.

Name Server

DNSSECDNSSEC

DNSSEC Usage Statistics · Download List of All Websites using DNSSEC

DNSSEC strengthens DNS authentication by using digital signatures based on public key cryptography.

Web Servers

ApacheApache

Apache Usage Statistics · Download List of All Websites using Apache

Apache has been the most popular web server on the Internet since April 1996.

Operating Systems and Servers