The Key management for IPSec is called the Internet Key Exchange (IKE)
Note: IKE underwent a series of improvements establishing IKEv2 with RFC 4306. The basis of this answer is IKEv2.
The IKE protocol is a hybrid of three other protocols: ISAKMP (Internet Security Association and Key Management Protocol), Oakley and SKEME. ISAKMP provides a framework for authentication and key exchange, but does not define them (neither authentication nor key exchange). The Oakley protocol describes a series of modes for key exchange and the SKEME protocol defines key exchange techniques.
IKE-Internet Key Exchange. A hybrid protocol that implements Oakley and Skeme key exchanges inside the ISAKMP framework. IKE can be used with other protocols, but its initial implementation is with the IPSec protocol. IKE provides authentication of the IPSec peers, negotiates IPSec keys, and negotiates IPSec security associations. IKE is implemented in accordance with RFC 2409, The Internet Key Exchange.
The Internet Key Exchange (IKE) security protocol is a key management protocol standard that is used in conjunction with the IPSec standard. IPSec can be configured without IKE, but IKE enhances IPSec by providing additional features, flexibility, and ease of configuration for the IPSec standard. IKE is a hybrid protocol that implements the Oakley key exchange and the SKEME key exchange inside the Internet Security Association and Key Management Protocol (ISAKMP) framework. (ISAKMP, Oakley, and SKEME are security protocols implemented by IKE.)
IKE automatically negotiates IPSec security associations (SAs) and enables IPSec secure communications without costly manual preconfiguration. Specifically, IKE provides these benefits:
Eliminates the need to manually specify all the IPSec security parameters in the crypto maps at both peers.
Allows you to specify a lifetime for the IPSec security association.
Allows encryption keys to change during IPSec sessions.
Allows IPSec to provide anti-replay services.
Permits certification authority (CA) support for a manageable, scalable IPSec implementation.
Allows dynamic authentication of peers.
About ISAKMP The Internet Security Association and Key Management Protocol (ISAKMP) is a framework that defines the phases for establishing a secure relationship and support for negotiation of security attributes, it does not establish sessions keys by itself, it is used along with the Oakley session key establishment protocol. The Secure Key Exchange Mechanism (SKEME) describes a secure exchange mechanism and Oakley defines the modes of operation needed to establish a secure connection.
ISAKMP provides a framework for Internet key management and provides the specific protocol support for negotiation of security attributes. Alone, it does not establish session keys. However it can be used with various session key establishment protocols, such as Oakley, to provide a complete solution to Internet key management. About Oakley The Oakley protocol uses a hybrid Diffie-Hellman technique to establish session keys on Internet hosts and routers. Oakley provides the important security property of Perfect Forward Secrecy (PFS) and is based on cryptographic techniques that have survived substantial public scrutiny. Oakley can be used by itself, if no attribute negotiation is needed, or Oakley can be used in conjunction with ISAKMP. When ISAKMP is used with Oakley, key escrow is not feasible.
The ISAKMP and Oakley protocols have been combined into a hybrid protocol. The resolution of ISAKMP with Oakley uses the framework of ISAKMP to support a subset of Oakley key exchange modes. This new key exchange protocol provides optional PFS, full security association attribute negotiation, and authentication methods that provide both repudiation and non-repudiation. Implementations of this protocol can be used to establish VPNs and also allow for users from remote sites (who may have a dynamically allocated IP address) access to a secure network.
About IPSec The IETF's IPSec Working Group develops standards for IP-layer security mechanisms for both IPv4 and IPv6. The group also is developing generic key management protocols for use on the Internet. For more information, refer to the IP Security and Encryption Overview.
IPSec is a framework of open standards developed by the Internet Engineering Task Force
(IETF) that provides security for transmission of sensitive information over unprotected
networks such as the Internet. It acts at the network level and implements the following
standards:
IPSec
Internet Key Exchange (IKE)
Data Encryption Standard (DES)
MD5 (HMAC variant)
SHA (HMAC variant)
Authentication Header (AH)
Encapsulating Security Payload (ESP)
IPSec services provide a robust security solution that is standards-based. IPSec also
provides data authentication and anti-replay services in addition to data confidentiality
services.
For more information regarding IPSec, refer to the chapter "Configuring IPSec Network
Security."
About SKEME
SKEME constitutes a compact protocol that supports a variety of realistic scenarios and
security models over Internet. It provides clear tradeoffs between security and performance
as required by the different scenarios without incurring in unnecessary system complexity.
The protocol supports key exchange based on public key, key distribution centers, or
manual installation, and provides for fast and secure key refreshment. In addition, SKEME
selectively provides perfect forward secrecy, allows for replaceability and negotiation of the
underlying cryptographic primitives, and addresses privacy issues as anonymity and
repudiatability
SKEME's basic mode is based on the use of public keys and a Diffie-Hellman shared
secret generation.
However, SKEME is not restricted to the use of public keys, but also allows the use of a
pre-shared key. This key can be obtained by manual distribution or by the intermediary of a
key distribution center (KDC) such as Kerberos.
In short, SKEME contains four distinct modes:
Basic mode, which provides a key exchange based on public keys and ensures PFS
thanks to Diffie-Hellman.
A key exchange based on the use of public keys, but without Diffie-Hellman.
A key exchange based on the use of a pre-shared key and on Diffie-Hellman.
A mechanism of fast rekeying based only on symmetrical algorithms.
In addition, SKEME is composed of three phases: SHARE, EXCH and AUTH.
During the SHARE phase, the peers exchange half-keys, encrypted with their respective
public keys. These two half-keys are used to compute a secret key K. If anonymity is
wanted, the identities of the two peers are also encrypted. If a shared secret already exists,
this phase is skipped.
The exchange phase (EXCH) is used, depending on the selected mode, to exchange either
Diffie-Hellman public values or nonces. The Diffie-Hellman shared secret will only be
computed after the end of the exchanges.
The public values or nonces are authenticated during the authentication phase (AUTH),
using the secret key established during the SHARE phase.
The messages from these three phases do not necessarily follow the order described
above; in actual practice they are combined to minimize the number of exchanged
messages.
References used for this question:
Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the
Ten Domains of Computer Security, John Wiley & Sons, 2001, Chapter 4: Cryptography
(page 172).
http://tools.ietf.org/html/rfc4306
http://tools.ietf.org/html/rfc4301
http://en.wikipedia.org/wiki/Internet_Key_Exchange
CISCO ISAKMP and OAKLEY information
CISCO Configuring Internet Key Exchange Protocol
http://www.hsc.fr/ressources/articles/ipsec-tech/index.html.en

Section: Network and Telecommunications
Explanation/Reference:
Packet filtering firewalls use routers with packet filtering rules to grant or deny access based on source address, destination address, and port.
They offer minimum security but at a very low cost, and can be an appropriate choice for a low-risk environment.
Source: TIPTON, Harold F. & KRAUSE, Micki, Information Security Management Handbook, 4th edition (volume 1), 2000, CRC Press, Chapter 3, Secured Connections to External Networks (page 60).

Explanation/Reference:
Source: HARRIS, Shon, All-In-One CISSP Certification Exam Guide, McGraw-Hill/Osborne, 2001, Page
644.

Asynchronous Communication transfers data by sending bits of data in irregular timing patterns.
In asynchronous transmission each character is transmitted separately, that is one character at a time. The character is preceded by a start bit, which tells the receiving end where the character coding begins, and is followed by a stop bit, which tells the receiver where the character coding ends. There will be intervals of ideal time on the channel shown as gaps. Thus there can be gaps between two adjacent characters in the asynchronous communication scheme. In this scheme, the bits within the character frame (including start, parity and stop bits) are sent at the baud rate.
The START BIT and STOP BIT including gaps allow the receiving and sending computers to synchronise the data transmission. Asynchronous communication is used when slow speed peripherals communicate with the computer. The main disadvantage of asynchronous communication is slow speed transmission. Asynchronous communication however, does not require the complex and costly hardware equipments as is required for synchronous transmission.
Asynchronous communication is transmission of data without the use of an external clock signal. Any timing required to recover data from the communication symbols is encoded within the symbols. The most significant aspect of asynchronous communications is variable bit rate, or that the transmitter and receiver clock generators do not have to be exactly synchronized.
The asynchronous communication technique is a physical layer transmission technique which is most widely used for personal computers providing connectivity to printers, modems, fax machines, etc.
An asynchronous link communicates data as a series of characters of fixed size and format. Each character is preceded by a start bit and followed by 1-2 stop bits.
Parity is often added to provide some limited protection against errors occurring on the link.
The use of independent transmit and receive clocks constrains transmission to relatively short characters (<8 bits) and moderate data rates (< 64 kbps, but typically lower).
The asynchronous transmitter delimits each character by a start sequence and a stop sequence. The start bit (0), data (usually 8 bits plus parity) and stop bit(s) (1) are transmitted using a shift register clocked at the nominal data rate.
When asynchronous transmission is used to support packet data links (e.g. IP), then special characters have to be used ("framing") to indicate the start and end of each frame transmitted.
One character (none as an escape character) is reserved to mark any occurrence of the special characters within the frame. In this way the receiver is able to identify which characters are part of the frame and which are part of the "framing".
Packet communication over asynchronous links is used by some users to get access to a network using a modem.
Most Wide Area Networks use synchronous links and a more sophisticated link protocol Source: KRUTZ, Ronald L. & VINES, Russel D., The CISSP Prep Guide: Mastering the Ten Domains of Computer Security, 2001, John Wiley & Sons, Page 100. and http://en.wikipedia.org/wiki/Asynchronous_communication and http://www.erg.abdn.ac.uk/users/gorry/course/phy-pages/async.html and http://www.ligaturesoft.com/data_communications/async-data-transmission.html

Section: Cryptography
Explanation/Reference:
NSA took the 128-bit algorithm Lucifer that IBM developed, reduced the key size to 64 bits and with that developed DES.
The following answers are incorrect:
Twofish. This is incorrect because Twofish is related to Blowfish as a possible replacement for DES.
Skipjack. This is incorrect, Skipjack was developed after DES by the NSA .
Brooks-Aldeman. This is incorrect because this is a distractor, no algorithm exists with this name.