Measurement, Monitoring & Sharing

The four key DORA metrics used to measure DevOps performance include which of the following sets?

• A CPU usage, memory usage, disk space, and network latency
• B Lines of code, number of meetings, bug count, server uptime
• C Deployment frequency, lead time for changes, change failure rate, and time to restore service ✓
• D Revenue, headcount, customer satisfaction, and marketing spend

Answer: The four DORA metrics are deployment frequency, lead time for changes, change failure rate, and mean time to restore service, which together measure both throughput and stability.

What is the main difference between monitoring and observability?

• A Monitoring is manual while observability is impossible to automate
• B They are identical concepts with different names
• C Observability applies only to hardware, monitoring only to software
• D Monitoring tracks known, predefined conditions; observability helps understand unknown internal states from system outputs ✓

Answer: Monitoring watches predefined metrics and known failure conditions, whereas observability uses logs, metrics, and traces to help teams understand and diagnose unexpected or unknown system behaviour.

In Site Reliability Engineering (SRE), what is an 'error budget'?

• A The acceptable amount of unreliability allowed before reliability work takes priority over new features ✓
• B A list of all known software defects
• C The number of engineers assigned to support
• D The financial budget allocated to fixing bugs

Answer: An error budget is the permissible level of unreliability derived from a service level objective; once it is exhausted, teams prioritise reliability work over releasing new features.

What does Mean Time To Restore (MTTR) measure?

• A The average time between two consecutive deployments
• B The average time taken to recover service after a failure or incident ✓
• C The total number of incidents in a year
• D The average time a feature spends in development

Answer: Mean Time To Restore measures how quickly a service is recovered after an incident, and a low MTTR indicates strong resilience and effective incident response.

Why is sharing knowledge through practices such as internal wikis, ChatOps, and post-incident reviews valued in DevOps?

• A It eliminates the need for any monitoring
• B It is only useful for external customers
• C It restricts information to a single expert team
• D It spreads learning, reduces single points of knowledge, and accelerates improvement across teams ✓

Answer: Sharing knowledge openly spreads learning, reduces dependence on individual experts, and helps the whole organisation improve faster, which is central to the Sharing pillar of CALMS.

In SRE, what is a Service Level Indicator (SLI)?

• A The name given to a deployment pipeline stage
• B A quantitative measure of a specific aspect of service performance, such as latency or availability ✓
• C A contract penalty clause for downtime
• D A list of customers using the service

Answer: A Service Level Indicator is a carefully chosen quantitative measure of an aspect of service performance, such as request latency or availability, used to assess whether objectives are being met.