Glossary / Network Segmentation
Network Segmentation
Dividing a network into smaller, isolated zones so that a compromise in one segment can't automatically reach every other system on the network.
Segmentation is implemented through VLANs, firewall rules between zones, or microsegmentation (isolation enforced per workload rather than per subnet), and its purpose is limiting lateral movement specifically — not just organizing traffic for performance or convenience.
A common, concrete example: guest Wi-Fi kept off the internal network, or a point-of-sale network segmented from general office traffic — the latter being a specific expectation under PCI-DSS. The segment boundary is what turns "one compromised laptop" into a contained incident instead of a path to the rest of the network.
Segmentation is cheap to design correctly during initial network setup and expensive to retrofit later onto a live, business-critical network — which is a large part of why it shows up disproportionately often in post-incident "what would have contained this" reviews, as the control that existed on paper but wasn't actually enforced.
How Nexus handles this
Nexus applies the same segmentation logic to its own architecture — tenant isolation enforced at both the application layer and PostgreSQL row-level security means one tenant's data is walled off from every other, the multi-tenant SaaS equivalent of segmenting a network so a breach in one zone doesn't reach the rest.
More terms
MSP (Managed Service Provider)
A company that remotely manages a client's IT infrastructure and end-user systems on an ongoing, proactive basis — usually a flat-fee contract, not break-fix billing.
RMM (Remote Monitoring and Management)
Software that lets an MSP monitor device health and perform remote management tasks — patching, scripting, remote control — across every client site from one console.
PSA (Professional Services Automation)
Software that runs the business side of MSP operations — ticketing, SLAs, billing, contracts, and client records — the system of record most MSP work flows through.
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