IT Service Management and Operations
This domain tests whether you can run IT as a service system rather than a set of silos. Expect questions on ITIL 4 concepts, incident and problem management, change enablement, service levels, and continual improvement.
The ITIL 4 service value system
The service value system links demand and opportunity to value through the service value chain: plan, improve, engage, design and transition, obtain/build, and deliver and support. Four dimensions must be balanced: organizations and people, information and technology, partners and suppliers, and value streams and processes. ITIL 4 defines 34 practices, not mandatory processes, and seven guiding principles, including focus on value, start where you are, progress iteratively with feedback, collaborate and promote visibility, think and work holistically, keep it simple and practical, and optimize and automate.
Service levels and error budgets
A service level indicator is the measured metric; a service level objective is the internal target; a service level agreement is the contract with consequences, often service credits. An error budget is the allowed unreliability implied by the SLO. Incident management restores service quickly; problem management removes root causes and maintains known errors; change enablement assesses risk and authorizes change. A change advisory board should focus on high-risk changes, not rubber-stamp every change.
Worked example
A 99.9% monthly availability SLO on a 30-day month allows 43,200 × 0.001 = 43.2 minutes of unavailability. One incident consumes 30 minutes, leaving 13.2 minutes. If cumulative downtime reaches 50 minutes, the SLO is breached. The team should freeze non-essential changes and prioritize reliability work. If the SLA is 99.5% with service credits, the SLA has not been breached, but the internal SLO has - and the SLO is the earlier warning signal.
Traps that cost marks
- Treating the SLO as the SLA, or promising 100% availability.
- Closing incidents without creating problem records for recurring causes.
- Measuring the service desk by tickets closed rather than restored service and satisfaction.
- Turning every practice into a heavy process.
- Using a CAB as the default approver for standard changes.
- Improving without a baseline and without measuring whether the change helped.