Communication and Network Security
Domain 4 covers network models and addressing, secure protocols, segmentation and modern architectures such as SDN and cloud networking, plus securing network components and communication channels including remote access.
Models, addressing and protocols
The OSI and TCP/IP models let you place a control at the right layer: routing and IP at the network layer, ports at the transport layer. IPv6 changes addressing, notably by dropping broadcast. Secure protocols such as IPsec, TLS and SSH replace cleartext predecessors.
Segmentation and architecture
Networks are divided physically (out-of-band, air-gapped) and logically (VLANs, VPNs, virtual routing), and increasingly micro-segmented so that east-west traffic between workloads is controlled, not just north-south traffic at the perimeter. SDN centralizes control logic, which makes the controller a critical asset.
Converged protocols and performance
Converged protocols carry storage, voice or other traffic over IP networks, bringing new exposure. Performance metrics matter for real-time traffic, and jitter rather than average delay is what breaks voice.
Network access and secure channels
Access to the network itself can be authenticated at the port with 802.1X. Remote access, administration and third-party connectivity each need encrypted, authenticated channels and deliberate choices about what traffic is protected.
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