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Added blog on BlueTooth Concerns for CompTIA Security+ (SY0-201 exam) here: http://sy0201.blogspot.com/2009/10/bluetooth-concerns.html

 When studying for Security+, you'll come across using RAID for disk redundancy.   RAID is short for redundant array of independent (or inexpensive) disks. Redundancy provides fault tolerance.  In other words, if a fault occurs in one drive, your system can tolerate the fault and continue to operate. Several different RAID types are available. When studying for Security+, you should be aware of the following topics.

• RAID-0 (also known as striping) does not provide any fault tolerance but increased performance.
• RAID-1 (also known as mirroring) uses two disks and provides fault tolerance. 
• RAID-5 (also known as striping with parity) uses at least three disks and provides fault tolerance while also providing increased performance. The equivalent of one drive is dedicated to parity.
• RAID-10 (also called 1+0) combines RAID 1 and RAID-0.  A variant is 0+1.  Both provide fault tolerance and increased performance for specific applications.

Both hardware and software RAID solutions are avaialble.  Hardware RAID is more expensive provides significantly better performance than sofware RAID.

Darril

One of the Security+ objectives is "Explain the purpose and application of virtualization technology."

 You may be wondering what this is about.  First, virtualization centers around virtualization desktop infrastructure (VDI) where a single physical computer can host multiple computer operating systems.  Many virtualization technologies exist such as VMWare and Microsoft's Virtual PC (upgraded and renamed to Windows Virtual PC in Windows 7).  I'm more familiar with Virtual PC (VPC) but the uses between brands are common. One great feature is that if something goes wrong with the virtual system, changes can be easily rolled back or undone.

As a simple example, I am running Windows 7 on my desktop PC and have a virtual mini-lab running on the system with Windows Server 2008 in one virtual system running as a domain controller, and a Windows 7 computer running as a client in the virtual domain. I have configured both of these two be able to communicate with each other but they are isolated from the host system or the Internet. 

From a security perspective, virtualization can be use for a few purposes.

• Testing of patches.  When patches for the operating system or applications are released, they can be applied in a virtual environment.  They can be tested here in a safe environment without any impact on the production environment.
• Testing of malware.  Once malware is discovered, security professionals want to know what it does and how it does it.  This often entails releasing it and observing what happens.  Again, a virtual environment is safe and won't impact the performance of the host operating system or the regular network.

Darril

Cryptography has several elements and an important one is the use of encryption.

 Encryption is used to enforce confidentiality (one of the three elements in the security triad of confidentiality, integrity and availability). If you want to keep your data secure and prevent unauthorized disclosure, you can encrypt the data to make it unreadable.

Encryption uses an algorithm and a key.  If either the algorithm is weak or the key is weak, the encryption can easily be broken.  Most algorthms are well known but keys are either frequently changed, or kept secret.

 Two major types of encryption are used: symmetric and assymmetric.

• Symmetric encryption uses a single key to both encrypt the data and decrypt the data.
• Asymmetric encryption uses two keys that are created as a matched pair (a public key and a private key).  Data encrypted with a public key can only be decrypted with the matching private key. Data encrypted with the private key can only be decrypted with the public key

The most popular type of symmetric encryption is AES.   AES is considered a fast, highly secure encryption algorithm. It is significantly faster (using less processor and memory resources) than both DES and 3DES. AES256 uses a key size of 256 bits.

 A Public Key Infrastrcuture (PKI) is required to support asymmetric encryption. Any entity can have a private key (which is always kept private). The matching public key is embedded in a certificate issued from a certificate authority (CA).

Darril