Network Isolation
Software Engineer path · lesson 88 of 99Understand VLANs, Security Groups, and Software-Defined Networking (SDN).
VLAN, security group or SDN?
Sort each description into the isolation technology.
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VLAN
Drop items hereSecurity group
Drop items hereSDN
Drop items hereTest your knowledge
If a Security Group is "stateful", what does that mean for outbound traffic if an inbound request on Port 80 is allowed?
The short version
VLANs are like putting up soundproof walls in an open-plan office. Security Groups are like a bouncer who remembers you—if he lets you outside to smoke, he automatically lets you back in (stateful). SDN is like having a central dispatcher (Control Plane) telling delivery drivers (Data Plane) exactly which routes to take.
In more depth
Network Isolation & Virtualization
Modern networking relies on logical isolation rather than physical separation.
VLAN (Virtual LAN)
Partitions a single physical switch into multiple distinct broadcast domains. Devices on different VLANs cannot communicate without a router.
Security Groups
Virtual, stateful firewalls that operate at the instance/VM level. "Stateful" means if a request is allowed in, the response is automatically allowed out.
SDN (Software-Defined Networking)
Separates the network into two planes:
Interview Questions
References & Further Reading
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