There are various types of backups and these are full, incremental, and differential. Let's look at these in turn:

• Full backup: A full backup is a backup of all of your data. However, some companies might only be able to back up all of their data over the weekend, so they will use either an incremental or differential midweek.
• Incremental: An incremental backup backs up the data since the last full backup or the last incremental. An incremental backup will need the full backup from the start and then all of the incremental backups.
• Differential: A differential backup will back up the data since the last full backup. The problem with this if we have a full backup at the start of the week and then a differential backup daily each day, they will be progressively larger each day. A differential backup will always be two tapes, the full backup from the start and the latest differential.

Example: We will compare the different types of backup. We will start the backup each day, but will suffer data loss on the Friday, and we will see how many tapes we need to recover our data. Our full backup will be 50 GB of data and each day we will produce 5 GB of data. You can see this from the following chart, how many tapes are needed for each type of backups to recover your data:

• • Full: The latest full backup is 65 GB; each day we back up more and more
  • Incremental: Starts off with the full backup but needs all of the incremental backup
  • Differential: Starts off with the full backup but needs the latest differential backup:

• Banner grabbing: Banner grabbing is a technique used to gain information about a remote server and is often used as part of a fingerprinting attack. This could be where you are looking for details on remote systems such as a web server. If you are looking for the patch level of a web server, we would use banner grabbing to collect this information.