An IT network audit is not just about scanning ports and listing switches. The value of an audit lies in its ability to produce evidence of operational mastery, not just a simple static inventory. Here we address the methodological points that make the difference between a usable deliverable and a document filed away without action.
Discrepancy between declared configuration and observed configuration: the real starting point
Most network audit guides start with mapping. This is necessary, but insufficient if it is limited to a raw SNMP export. The first reflex should be to confront the declared configuration (CMDB, internal documentation, architecture diagrams) with the configuration actually observed on the equipment.
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A switch whose VLAN table does not match the official network diagram poses an immediate risk. A firewall whose active rules diverge from the documented security policy invalidates any displayed compliance. Every discrepancy between declared and observed must be timestamped and traced, identifying who collected the information and under what conditions.
This approach transforms the audit into an enforceable proof, particularly within the framework of the NIS2 directive, which requires reasoning in terms of documented compliance scope. It is no longer enough to check technical boxes: the audited entity must formally justify the chosen scope, including the classification of subsidiaries and interconnections with third parties. To successfully conduct an IT network audit, this documentary rigor weighs as much as the technical analysis itself.
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Network resilience tests: failover, switches, and effective restoration
Many audits stop at identifying vulnerabilities. They produce a report of vulnerabilities ranked by severity, then move on to the action plan. The missing link is the controlled resilience test.
An untested recovery plan is not a recovery plan. We recommend systematically integrating three operational checks into the audit scope:
- WAN link or firewall cluster failover under real conditions, measuring the actual downtime and comparing it to the announced RTO
- Restoration of a complete network backup (configuration of active equipment, filtering rules, certificates) in an isolated environment to validate file integrity
- Simulation of the loss of a critical node (Wi-Fi controller, internal DHCP/DNS server) to observe network behavior without human intervention
These tests reveal vulnerabilities invisible to mapping. An active/passive cluster that takes several minutes to failover instead of a few seconds indicates a heartbeat or priority misconfiguration issue. A configuration backup that does not restore correctly invalidates any continuity strategy.
Network security posture: going beyond vulnerability scanning
Recent network audits are no longer limited to VLANs, ACLs, and open ports. The notion of security posture now incorporates organizational elements that condition technical robustness.
First point: log centralization. A network whose active equipment does not send its logs to a centralized collector (syslog, SIEM) is a blind network. The audit must verify that logs are collected, timestamped via NTP, and retained for a duration consistent with regulatory obligations (GDPR, NIS2).
Second point: access policies for administrative equipment. We regularly observe SSH or HTTPS access to switches and routers open from any user VLAN, without restrictions by management ACL. Access to the management plane must be segmented and limited to a dedicated VLAN, with centralized authentication (RADIUS or TACACS+).
Third point: firmware. A network device whose firmware has not been updated for several years accumulates known CVEs. The audit must cross-reference the installed version with the manufacturer’s security bulletins for each active device.
NIS2 compliance and network cybersecurity
The NIS2 directive expands the scope of affected entities, including SMEs in critical sectors. For these companies, the network audit is no longer optional. It becomes a building block of compliance demonstration, alongside risk analysis or incident management plans. The audit deliverable must therefore be structured to serve as supporting documentation in case of inspection.
Network audit deliverable: structuring a usable report
An audit report that lists hundreds of findings without prioritization or business context ends up in a drawer. The quality of the deliverable determines the actual impact of the audit on the infrastructure.
Each finding must be linked to a concrete business risk. An open TCP port on a production server does not carry the same criticality depending on whether it exposes a customer database or an internal monitoring service. The report must clarify this difference.
We recommend structuring the deliverable into three levels:
- Executive summary intended for management, with major risks translated into business impact (downtime, data loss, regulatory non-compliance)
- Detailed technical report for the infrastructure team, with collected evidence, configuration captures, and observed discrepancies
- Prioritized remediation plan with effort estimation, identified responsible parties, and deadlines, ranked by decreasing criticality
This breakdown allows each stakeholder to find the information at their reading level, without drowning the IT department in technical details or leaving management without a consolidated view.
Post-audit follow-up and cost management
The report does not close the audit. A three-month follow-up allows verifying that critical remediations have been applied, that corrected configurations have not regressed, and that monitoring tools cover identified blind spots. Without this follow-up, the majority of planned remediations are never implemented.
The network audit in a company gains relevance when treated as a recurring process, not as a one-time event. Planning an annual cycle, aligned with compliance deadlines and infrastructure changes (cloud migration, SD-WAN deployment), ensures that the network remains aligned with the real needs of systems and users.