Differential backups are described as selecting files changed since which point?

Differential backups are described as selecting files changed since which point?

• A. The last backup
• B. The first backup
• C. The last month
• D. The entire data set

Answer: (A)

Differential backups record all changes since a fixed starting point, which for this type of backup is the last full backup. That means each differential includes every file that has changed since that full backup, growing as more changes occur until the next full backup resets the baseline. When restoring, you’d apply the full backup first and then the latest differential to update to the current state. The other options don’t fit because the last backup would imply changes since the most recent backup of any type (that’s how incremental backups work), the last month isn’t a fixed baseline unless you explicitly did a full backup then, and backing up the entire data set would defeat the purpose of tracking only changes.

Differential backups record all changes since a fixed starting point, which for this type of backup is the last full backup. That means each differential includes every file that has changed since that full backup, growing as more changes occur until the next full backup resets the baseline. When restoring, you’d apply the full backup first and then the latest differential to update to the current state. The other options don’t fit because the last backup would imply changes since the most recent backup of any type (that’s how incremental backups work), the last month isn’t a fixed baseline unless you explicitly did a full backup then, and backing up the entire data set would defeat the purpose of tracking only changes.