Section: Security Operation Adimnistration
Explanation/Reference:
Availability is making sure that the data is accessible when and where it is needed.
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 59.

Section: Risk, Response and Recovery
Explanation/Reference:
Internal Hot Site-This site is standby ready with all the technology and equipment necessary to run the applications positioned there. The planner will be able to effectively restart an application in a hot site recovery without having to perform any bare metal recovery of servers. If this is an internal solution, then often the organization will run non-time sensitive processes there such as development or test environments, which will be pushed aside for recovery of production when needed. When employing this strategy, it is important that the two environments be kept as close to identical as possible to avoid problems with O/S levels, hardware differences, capacity differences, etc., from preventing or delaying recovery.
Recovery Site Strategies Depending on how much downtime an organization has before the technology recovery must be complete, recovery strategies selected for the technology environment could be any one of the following:
Dual Data Center-This strategy is employed for applications, which cannot accept any downtime without negatively impacting the organization. The applications are split between two geographically dispersed data centers and either load balanced between the two centers or hot swapped between the two centers. The surviving data center must have enough head room to carry the full production load in either case.
External Hot Site-This strategy has equipment on the floor waiting, but the environment must be rebuilt for the recovery. These are services contracted through a recovery service provider. Again, it is important that the two environments be kept as close to identical as possible to avoid problems with O/S levels, hardware differences, capacity differences, etc., from preventing or delaying recovery. Hot site vendors tend to have the most commonly used hardware and software products to attract the largest number of customers to utilize the site.
Unique equipment or software would generally need to be provided by the organization either at time of disaster or stored there ahead of time.
Warm Site-A leased or rented facility that is usually partially configured with some equipment, but not the actual computers. It will generally have all the cooling, cabling, and networks in place to accommodate the recovery but the actual servers, mainframe, etc., equipment are delivered to the site at time of disaster.
Cold Site-A cold site is a shell or empty data center space with no technology on the floor. All technology must be purchased or acquired at the time of disaster.
Reference(s) used for this question:
Hernandez CISSP, Steven (2012-12-21). Official (ISC)2 Guide to the CISSP CBK, Third Edition ((ISC)2 Press) (Kindle Locations 21265-21291). Auerbach Publications. Kindle Edition.

Explanation/Reference:
Rule-based access control is a type of non-discretionary access control because this access is determined by rules and the subject does not decide what those rules will be, the rules are uniformly applied to ALL of the users or subjects.
In general, all access control policies other than DAC are grouped in the category of non-discretionary access control (NDAC). As the name implies, policies in this category have rules that are not established at the discretion of the user. Non-discretionary policies establish controls that cannot be changed by users, but only through administrative action.
Both Role Based Access Control (RBAC) and Rule Based Access Control (RuBAC) fall within Non Discretionary Access Control (NDAC). If it is not DAC or MAC then it is most likely NDAC.
IT IS NOT ALWAYS BLACK OR WHITE
The different access control models are not totally exclusive of each others. MAC is making use of Rules to be implemented. However with MAC you have requirements above and beyond having simple access rules. The subject would get formal approval from management, the subject must have the proper security clearance, objects must have labels/sensitivity levels attached to them, subjects must have the proper security clearance. If all of this is in place then you have MAC.
BELOW YOU HAVE A DESCRIPTION OF THE DIFFERENT CATEGORIES:
MAC = Mandatory Access Control
Under a mandatory access control environment, the system or security administrator will define what permissions subjects have on objects. The administrator does not dictate user's access but simply configure the proper level of access as dictated by the Data Owner.
The MAC system will look at the Security Clearance of the subject and compare it with the object sensitivity level or classification level. This is what is called the dominance relationship.
The subject must DOMINATE the object sensitivity level. Which means that the subject must have a security clearance equal or higher than the object he is attempting to access.
MAC also introduce the concept of labels. Every objects will have a label attached to them indicating the classification of the object as well as categories that are used to impose the need to know (NTK) principle.
Even thou a user has a security clearance of Secret it does not mean he would be able to access any Secret documents within the system. He would be allowed to access only Secret document for which he has a Need To Know, formal approval, and object where the user belong to one of the categories attached to the object.
If there is no clearance and no labels then IT IS NOT Mandatory Access Control.
Many of the other models can mimic MAC but none of them have labels and a dominance relationship so they are NOT in the MAC category.
NISTR-7316 Says:
Usually a labeling mechanism and a set of interfaces are used to determine access based on the MAC policy; for example, a user who is running a process at the Secret classification should not be allowed to read a file with a label of Top Secret. This is known as the "simple security rule," or "no read up." Conversely, a user who is running a process with a label of Secret should not be allowed to write to a file with a label of Confidential. This rule is called the "*-property" (pronounced "star property") or "no write down." The *-property is required to maintain system security in an automated environment. A variation on this rule called the "strict *-property" requires that information can be written at, but not above, the subject's clearance level. Multilevel security models such as the Bell-La Padula Confidentiality and Biba Integrity models are used to formally specify this kind of MAC policy.
DAC = Discretionary Access Control
DAC is also known as: Identity Based access control system.
The owner of an object is define as the person who created the object. As such the owner has the discretion to grant access to other users on the network. Access will be granted based solely on the identity of those users.
Such system is good for low level of security. One of the major problem is the fact that a user who has access to someone's else file can further share the file with other users without the knowledge or permission of the owner of the file. Very quickly this could become the wild wild west as there is no control on the dissimination of the information.
RBAC = Role Based Access Control
RBAC is a form of Non-Discretionary access control.
Role Based access control usually maps directly with the different types of jobs performed by employees within a company.
For example there might be 5 security administrator within your company. Instead of creating each of their profile one by one, you would simply create a role and assign the administrators to the role. Once an administrator has been assigned to a role, he will IMPLICITLY inherit the permissions of that role.
RBAC is great tool for environment where there is a a large rotation of employees on a daily basis such as a very large help desk for example.
RBAC or RuBAC = Rule Based Access Control
RuBAC is a form of Non-Discretionary access control.
A good example of a Rule Based access control device would be a Firewall. A single set of rules is imposed to all users attempting to connect through the firewall.
NOTE FROM CLEMENT:
Lot of people tend to confuse MAC and Rule Based Access Control.
Mandatory Access Control must make use of LABELS. If there is only rules and no label, it cannot be Mandatory Access Control. This is why they call it Non Discretionary Access control (NDAC).
There are even books out there that are WRONG on this subject. Books are sometimes opiniated and not strictly based on facts.
In MAC subjects must have clearance to access sensitive objects. Objects have labels that contain the classification to indicate the sensitivity of the object and the label also has categories to enforce the need to know.
Today the best example of rule based access control would be a firewall. All rules are imposed globally to any user attempting to connect through the device. This is NOT the case with MAC.
I strongly recommend you read carefully the following document:
NISTIR-7316 at http://csrc.nist.gov/publications/nistir/7316/NISTIR-7316.pdf It is one of the best Access Control Study document to prepare for the exam. Usually I tell people not to worry about the hundreds of NIST documents and other reference. This document is an exception. Take some time to read it.
Reference(s) used for this question:
KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 33.
and
NISTIR-7316 at http://csrc.nist.gov/publications/nistir/7316/NISTIR-7316.pdf and
Conrad, Eric; Misenar, Seth; Feldman, Joshua (2012-09-01). CISSP Study Guide (Kindle Locations 651-
652). Elsevier Science (reference). Kindle Edition.

Section: Network and Telecommunications
Explanation/Reference:
Many times when a connection is opened, the firewall will inspect all layers of the packet. While this inspection is scaled back for subsequent packets to improve performance, this is the best of the four answers.
When packet filtering is used, a packet arrives at the firewall, and it runs through its ACLs to determine whether this packet should be allowed or denied. If the packet is allowed, it is passed on to the destination host, or to another network device, and the packet filtering device forgets about the packet. This is different from stateful inspection, which remembers and keeps track of what packets went where until each particular connection is closed. A stateful firewall is like a nosy neighbor who gets into people's business and conversations. She keeps track of the suspicious cars that come into the neighborhood, who is out of town for the week, and the postman who stays a little too long at the neighbor lady's house. This can be annoying until your house is burglarized. Then you and the police will want to talk to the nosy neighbor, because she knows everything going on in the neighborhood and would be the one most likely to know something unusual happened.
"Inspected at only one Open Systems Interconnetion (OSI) layer" is incorrect. To perform stateful packet inspection, the firewall must consider at least the network and transport layers.
"Decapsulated at all Open Systems Interconnection (OSI) layers" is incorrect. The headers are not stripped ("decapsulated" if there is such a word) and are passed through in their entirety IF the packet is passed.
"Encapsulated at all Open Systems Interconnect (OSI) layers" is incorrect. Encapsulation refers to the adding of a layer's header/trailer to the information received from the above level. This is done when the packet is assembled not at the firewall.
Reference(s) used for this question:
CBK, p. 466
Harris, Shon (2012-10-25). CISSP All-in-One Exam Guide, 6th Edition (pp. 632-633). McGraw-Hill. Kindle Edition.

Secure shell (SSH) was designed as an alternative to some of the insecure protocols and allows users to securely access resources on remote computers over an encrypted tunnel. The Secure Shell Protocol (SSH) is a protocol for secure remote login and other secure network services over an insecure network. The SSH authentication protocol runs on top of the SSH transport layer protocol and provides a single authenticated tunnel for the SSH connection protocol.
SSH's services include remote log-on, file transfer, and command execution. It also supports port forwarding, which redirects other protocols through an encrypted SSH tunnel. Many users protect less secure traffic of protocols, such as X Windows and VNC (virtual network computing), by forwarding them through a SSH tunnel.
The SSH tunnel protects the integrity of communication, preventing session hijacking and other man-in-the-middle attacks. Another advantage of SSH over its predecessors is that it supports strong authentication. There are several alternatives for SSH clients to authenticate to a SSH server, including passwords and digital certificates.
Keep in mind that authenticating with a password is still a significant improvement over the other protocols because the password is transmitted encrypted.
There are two incompatible versions of the protocol, SSH-1 and SSH-2, though many servers support both. SSH-2 has improved integrity checks (SSH-1 is vulnerable to an insertion attack due to weak CRC-32 integrity checking) and supports local extensions and additional types of digital certificates such as Open PGP. SSH was originally designed for UNIX, but there are now implementations for other operating systems, including Windows, Macintosh, and OpenVMS.
Is SSH 3.0 the same as SSH3? The short answer is: NO SSH 3.0 refers to version 3 of SSH Communications SSH2 protocol implementation and it could also refer to OpenSSH Version 3.0 of its SSH2 software. The "3" refers to the software release version not the protocol version. As of this writing (July 2013), there is no SSH3 protocol.
"Server authentication" is incorrect. Though many SSH clients allow pre-caching of server/host keys, this is a minimal form of server/host authentication.
"Host authentication" is incorrect. Though many SSH clients allow pre-caching of server/host keys, this is a minimal form of server/host authentication.
"Guest authentication" is incorrect. The general idea of "guest" is that it is unauthenticated access.
Reference(s) used for this question:
http://www.ietf.org/rfc/rfc4252.txt Hernandez CISSP, Steven (2012-12-21). Official (ISC)2 Guide to the CISSP CBK, Third Edition ((ISC)2 Press) (Kindle Locations 7080-7088). Auerbach Publications. Kindle Edition.