NATO is currently in a ‘grey zone’: increasingly being challenged in cyberspace while unable to attribute attacks, thus failing to deter. Simultaneously, many governments, businesses, and populations depend on the Internet and the cloud to function properly. This is a dangerous situation, since global Internet connectivity could get disrupted and destabilised. This chapter explains the basic principles from an overall technological perspective, and discusses the challenge of anti-access and area denial (A2/AD) in the context of global Internet disruptions. What is the contested area, what are possible effects, and can those effects be limited? Using a layered approach, we define the cyber ‘high ground’ as maintenance of and control over critical infrastructure, from core to edge, from hardware to software. To ensure each cyber ‘area’ can be protected in isolation but still allow...