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Chapter I
They should develop mitigation and recovery measures, defensive cyberspace operations
(DCO) priorities, primary/secondary/tertiary communication means, and measures to ensure
critical data reliability. When the staff perceives that they cannot trust data on a network, or
segment of the network, they should stop using the network/segment. In fact, the perception
of data unreliability may unnecessarily extend beyond the specific degraded segment.
Therefore, it is imperative that the staff be informed of network/segment status as quickly as
possible.
2. Cyberspace
a. Cyberspace, while a global domain within the information environment, is one of five
interdependent domains, the others being the physical domains of air, land, maritime, and
space. Much as air operations rely on air bases or ships in the land and maritime domains,
CO rely on an interdependent network of IT infrastructures, including the Internet,
telecommunications networks, computer systems, and embedded processors and controllers,
and the content that flows across and through these components. CO rely on links and nodes
that reside in the physical domains and perform functions experienced both in cyberspace
and the physical domains. For example, network servers may reside in a land-based data
complex or at sea aboard warships, and wireless network transmissions pass through air and
space and even underwater. Similarly, activities in cyberspace can enable freedom of action
for activities in the physical domains. Activities in the physical domains can create effects in
and through cyberspace by affecting the electromagnetic spectrum (EMS), or the physical
infrastructure. The relationship between space and cyberspace is unique in that virtually all
space operations depend on cyberspace, and a critical portion of cyberspace can only be
provided via space operations. Space provides a key global connectivity option for CO.
Conversely, CO provide a means by which space support is executed. These interrelationships
are important considerations across the spectrum of CO, and particularly when
conducting targeting in cyberspace (see Chapter IV, “Planning and Coordination”).
b. Cyberspace consists of many different and often overlapping networks, as well as the
nodes (any device or logical location with an internet protocol [IP] address or other
analogous identifier) on those networks, and the system data (such as routing tables) that
support them. Though not all nodes and networks are globally connected or accessible,
cyberspace continues to become increasingly interconnected. Networks can be intentionally
isolated or subdivided into enclaves using access controls, encryption, disparate protocols, or
physical separation. With the exception of physical separation, none of these approaches
eliminate underlying physical connectivity; instead they limit access. Achieving CO access
may be affected by legal, sovereignty, policy, informational environment, or operational
limitations; however, adjusting to limitations does not necessarily allow access to a target.
c. Cyberspace can be described in terms of three layers: physical network, logical
network, and cyber-persona (Figure I-1). Each of these represents a level on which CO may
be conducted.
(1) The physical network layer of cyberspace is comprised of the geographic
component and the physical network components. It is the medium where the data travel.
The geographic component is the location in land, air, sea, or space where elements of the
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