Technical Trade SchoolBAS-400 developer-series
BAS-406
Ten concept and evidence figures

BAS-406 Visual Aid Library

Figure-use rule

Each figure is an orientation and reasoning aid, not a project drawing. Learners must pair it with the current sequence, point list, wiring/piping documents, manufacturer instructions, and as-found evidence.

Figure 1 — Station role, architecture, scope, inventory, and requirements critical

Normal-rule anchor

A station is part of an OT system, not an isolated software file; recovery depends on hardware, OS/platform, network, identity, licenses, certificates, databases, controllers, and external services.

Case overlay

The owner requests a replacement supervisor but provides only a station backup and an old IP list.

Calculation/evidence callout: Reconcile required, discovered, documented, backed-up, restorable, and unknown assets/dependencies.

Figure 2 — Platform, OS, time, DNS, certificates, and licensing critical

Normal-rule anchor

A station can start and still be unrecoverable or insecure when time, certificates, DNS, licensing, compatibility, or entitlement is undocumented.

Case overlay

A restored station has a different hostname, expired certificate, five-minute clock offset, and a license bound to old hardware.

Calculation/evidence callout: Calculate clock offset, certificate/license time remaining, resource compatibility, and required maintenance window.

Figure 3 — Identity, RBAC, accounts, and secure remote access critical

Normal-rule anchor

Technical connectivity is not authorization; remote access must be deliberate, attributable, limited, monitored, and closed.

Case overlay

A vendor asks for permanent administrator access through a shared VPN account to troubleshoot one controller.

Calculation/evidence callout: Count users/roles/privileges, stale or shared accounts, session duration, approved targets, and closure evidence.

Figure 4 — Networks, drivers, device discovery, and segmentation critical

Normal-rule anchor

Discovery and broad firewall access can affect production; use approved boundaries, explicit targets, least functionality, and monitored tests.

Case overlay

A new supervisor sees duplicate BACnet devices across routed networks and floods a slow field bus with polling.

Calculation/evidence callout: Calculate address/subnet membership, poll load, timeout/retry impact, duplicate instances, and permitted flow matrix coverage.

Figure 5 — Station databases and core services

Normal-rule anchor

A station archive that omits external databases, certificates, licenses, drivers, or secrets is not a complete recovery capability.

Case overlay

Trends restore but alarm recipients, certificates, and custom driver modules do not.

Calculation/evidence callout: Inventory service records, retention/storage, dependency coverage, and restore pass/fail by function.

Figure 6 — Resources, capacity, performance, health, and monitoring

Normal-rule anchor

A larger resource allocation does not correct unbounded history, alarm floods, driver retries, database corruption, or bad program design.

Case overlay

Station memory rises daily while a driver reconnects and an alarm storm expands the database.

Calculation/evidence callout: Calculate utilization, growth rate, time-to-capacity, event/record rate, latency percentile, and before/after baseline difference.

Figure 7 — Backup scope, frequency, protection, retention, and 3-2-1 strategy critical

Normal-rule anchor

A backup is a claim until its contents, integrity, ownership, protection, retention, and recovery use are tested.

Case overlay

The only archive is stored on the running supervisor and is overwritten after each change.

Calculation/evidence callout: Calculate RPO coverage, copy/media/location counts, retention generations, storage requirement, checksum match, and dependency coverage.

Figure 8 — Restore testing, dependencies, secrets, licenses, and functional proof critical

Normal-rule anchor

Restore success means the approved recovery acceptance tests pass; a file that imports without error is insufficient.

Case overlay

A station opens after restore but cannot authenticate controllers, route alarms, or decrypt saved credentials.

Calculation/evidence callout: Measure RTO, compare to objective, reconcile restored functions/dependencies, and verify checksums and data recency.

Figure 9 — Patching, upgrades, compatibility, migration, and rollback critical

Normal-rule anchor

A current version is not automatically safer when unsupported dependencies, untested migration, or no recoverable rollback create greater operational risk.

Case overlay

A security patch requires a platform upgrade that changes database schema and drops support for a legacy driver.

Calculation/evidence callout: Reconcile dependency compatibility, test coverage, downtime estimate, migration duration, resource margin, and rollback feasibility.

Figure 10 — Disaster-recovery exercise, documentation, turnover, and as-left defense critical

Normal-rule anchor

A recovery plan improves through exercised evidence; untested steps, unavailable people, hidden credentials, and undocumented dependencies are findings, not assumptions.

Case overlay

The primary supervisor fails during occupied hours and the designated backup operator cannot locate the current recovery package.

Calculation/evidence callout: Measure detection, decision, restore, and validation times; reconcile objectives, results, gaps, owners, and retest dates.