Hot site

A hot site is a fully equipped alternate processing facility: hardware, software, network connectivity, and current data are all in place, kept current by near-real-time replication or frequent synchronisation. When disaster strikes the primary site, operations can switch over within hours or less, because nothing needs to be procured, installed, or restored beyond the final increment of data. It is the recovery option an organisation chooses when downtime is measured in money per minute.

That readiness is why the hot site is the most expensive option: the organisation is effectively running a second data centre, with duplicate equipment, licences, and the bandwidth to keep data current. The choice between hot, warm, and cold sites is not a technical decision but a cost calculation against the RTO: the site must be able to restore service inside the recovery time objective the business has set, and no cheaper option that misses that target is acceptable.

Exam relevance: if a scenario gives an RTO of minutes to a few hours, or describes real-time data replication to a standby facility, the answer is hot site. The classic confusable is the warm site, which has the equipment but not current data: its recovery is measured in days because backups must be restored first. Cost questions invert the ranking: the hot site wins on speed and loses on price, every time.