From Wikipedia:
Terahertz radiation occupies a middle ground between microwaves and infrared light waves, and technology for generating and manipulating it is in its infancy, and is the subject of research. This lack of technology is called the terahertz gap. It represents the region in the electromagnetic spectrum that the frequency of electromagnetic radiation becomes too high to be measured by digitally counting cycles using electronic counters, and must be measured by the proxy properties of wavelength and energy. Similarly, in this frequency range the generation and modulation of coherent electromagnetic signals ceases to be possible by the conventional electronic devices used to generate radio waves and microwaves, and requires new devices and techniques.
In your firewall:
1. Whitelist destination IPs for destination port 53, workflow denials adding IPs that have reverse DNS entries. (e.g. don't allow access to fly-by night DNS servers)
2. Whitelist source IPs for destination port 53. (E.g. do not allow alternate DNS servers to be used inside your org)
Have your org's DNS servers point to OpenDNS or GoogleDNS -- they do a good job of filtering out the rifraf
The brain is a wonderful organ; it starts working the moment you get up in the morning, and does not stop until you get to work.