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CITP: Information Systems and Infrastructure

CITP · Work through your exam, one topic at a time.

All guide sections

Information Systems and Infrastructure

Domain 2 covers Information Systems and Infrastructure. The exam tests whether you understand the components that deliver processing and can reason about availability, integrity, and recovery - not whether you can configure a router.

The stack

Hardware and operating systems host virtualization and containers; networks move data using TCP/IP across LANs and WANs; database management systems store data under ACID properties (atomicity, consistency, isolation, durability); applications such as ERP and CRM sit on top. Cloud service models shift control: IaaS gives infrastructure, PaaS gives a platform, SaaS gives a finished application. Deployment can be public, private, or hybrid, and under the shared-responsibility model the provider secures the cloud while the customer secures what it puts in the cloud.

Availability and recovery

Recovery time objective (RTO) is the maximum acceptable downtime; recovery point objective (RPO) is the maximum acceptable data loss, measured in time. A full backup copies everything; an incremental copies changes since the last backup of any type; a differential copies changes since the last full backup. Restoring incrementals requires the full plus every incremental in sequence. RAID improves availability and performance but is not a backup. Hot sites are ready near-instantly, warm sites are partially equipped, and cold sites provide space only.

Worked example

A payment processor promises merchants recovery within four hours and no more than 15 minutes of lost transactions. Its design is a nightly full backup plus hourly log shipping to a warm site.

Reasoning: the four-hour RTO is achievable only if the warm site is genuinely equipped and activation is rehearsed. The 15-minute RPO fails: hourly log shipping can lose up to 60 minutes, and the nightly full alone would lose up to 24 hours. Logs must ship at least every 15 minutes, restores must be tested, and copies should be held outside the primary region.

Traps

  • Swapping RTO and RPO.
  • Mixing up incremental and differential restore chains.
  • Treating RAID as backup.
  • Assuming the cloud provider backs up customer data or owns customer risk.
  • Equating a warm site with automatic failover.