Recovery sites appear again and again in CISA preparation, under Domain 4: Information Systems Operations and Business Resilience. The concept is simple once you see it as a trade-off between speed and cost.
The three main types of recovery site
| Site | What is in place | Typical recovery |
|---|---|---|
| Hot site | Fully configured: hardware, software, network and data ready to run | Within hours, or even minutes |
| Warm site | Partially configured: network connections and some equipment, but not the main computer | Days |
| Cold site | Only the basic environment: power, cooling, space and flooring. No computer equipment | Weeks |
Two more you may meet: a mobile site (a specially designed trailer that can be moved to where it is needed) and a reciprocal agreement (two organisations agree to use each other's facilities in a disaster).
Faster recovery means higher cost
A hot site is the fastest and the most expensive, because you are paying for a second, ready-to-run environment. A cold site is the cheapest and the slowest. The recovery time objective (RTO), the maximum acceptable downtime agreed by the business, decides which one is appropriate:
- RTO of a few hours → hot site
- RTO of a few days → warm site may be acceptable
- RTO of weeks → a cold site may be enough
Practice question
A bank's payment system must be running again within a few hours of a disaster. Which recovery option BEST meets this requirement?
- A. Cold site with an equipment delivery contract
- B. Warm site with network connections in place
- C. Hot site with fully configured systems
- D. Reciprocal agreement with a partner bank
Answer: C. Only a hot site is ready to operate within hours.
Why not the others?
- A, cold site: a delivery contract helps, however equipment still has to arrive, be installed and configured, which takes days or weeks.
- B, warm site: network connectivity is valuable, however the main computer is missing, so recovery cannot happen within hours.
- D, reciprocal agreement: it is cheap, however capacity is not guaranteed when you need it and such agreements are hard to test and enforce.
The exam trap
Many candidates assume a warm site already has the main computer. It does not. A warm site has network connections and selected peripheral equipment; only a hot site is ready to run.
Keep the qualifier in mind as well: when a question asks for the BEST option, more than one answer may work eventually. Pick the one that meets the stated requirement, here, recovery within hours.
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