thinQmaster Virtual testing partner Adaptive practice exams that find your weak spots and drill them. Every answer explained. From $69
Enroll

thinQmaster

Find your exam

Five questions free, before you decide.

Step 1 · choose a vendor

In one of our camps? Your practice exams come with the tuition — they are on your study page already.

Security Operations · Foundational

3-2-1 Backup Rule

A backup guideline: keep three copies of data on two different media types with one copy offsite.

Definition

The rule protects against device failure, site disasters and ransomware. Modern variants such as 3-2-1-1-0 add one offline or immutable copy and zero errors after verification. Regular restore testing confirms backups are usable.

Example

Production data, a local backup appliance copy and an immutable cloud copy.

Exam tip

Offline or immutable copies are the key ransomware protection.

Related terms