Grid computing is a system that is very large scaled, distributed, and virtualized.
Answer option C is incorrect. Cloud computing is about delivering software or operating systems as a service, rather than installing them locally.
Answer option A is incorrect. Edge computing is about load balancing servers, literally on the edge of the network.
Answer option D is incorrect. Virtualized computing is about the way the system is hosted, not necessarily the servers distribution {as with cloud and grid computing).

Certification authority (CA) is an entity in a network, which manages security credentials and public keys for message encryption. It issues certificates that confirm the identity and other attributes of a certificate in relation to other entities. Depending on the public key infrastructure implementation, a certificate includes the owners name, the owner's public key, information about the public key owner, and the expiry date of the certificate.
Answer option B is incorrect. CRL stands for Certificate Revocation List. In CRL, the certificates that are revoked by the Certificate Authority (CA) are mentioned. It becomes necessary for NetScreen to check the status of certificates received against a CRL to ensure their validity in phase 1 negotiation. The firewall recovers the CRL that is defined in the CRL certificate if a CRL is not loaded into the NetScreens database. The firewall attempts to recover the CRL defined in the CA certificate by means of LDAP or HTTP. In case the CRL is not defined in the CA certificate it can use the URL defined by the user for the CRL.
Answer option D is incorrect. Online Certificate Status Protocol (OCSP) is used for obtaining the revocation status of an X.509 digital certificate. It is used to verify the status of a certificate. It was created as an alternative to certificate revocation lists (CRL). It provides more timely information about the revocation status of a certificate. It also eliminates the need for clients to retrieve the CRLs themselves. Therefore, it generates to less network traffic and provides better bandwidth management. It is described in RFC
2560 and is on the Internet standards track.
Answer option C is incorrect. A PKI (public key infrastructure) enables users of a basically unsecured public network such as the Internet to securely and privately exchange data and money through the use of a public and a private cryptographic key pair that is obtained and shared through a trusted authority. The public key infrastructure assumes the use of public key cryptography, which is the most common method on the Internet for authenticating a message sender or encrypting a message.

A programmer writes, tests, debugs, and maintains the detailed instructions in computer programs that computers follow for performing their functions. He also conceives, designs, and tests logical structures in order to solve computer problems. A number of technical innovations in programming, advanced computing technologies, and sophisticated programming languages and tools have redefined the role of a programmer in an organization.
Answer options B and C are incorrect. A database administrator develops and designs database strategies, monitors and improves database performance and capacity, and plans for future expansion requirements. He also plans, co-ordinates and implements security measures for safety of the organization's database. A database administrator is also known as database coordinator or database programmer. He is closely related to the database analyst, database modeler, programmer analyst, and systems manager.

Explanation: Answer option C is correct. Following are the three levels of likelihood:
* High: In this level, the threat-source is highly motivated and sufficiently capable, and controls to prevent the vulnerability from being exercised are ineffective.
* Medium: In this level the threat-source is motivated and capable, but controls are in place that may impede successful exercise of the vulnerability.
* Low: In this level, the threat-source lacks motivation or capability, or controls are in place to prevent, or at least significantly impede, the vulnerability from being exercised.

Intermittent problems require isolation before any solution can be found. It is important to limit possible causes. This is done by isolating the network segment. By slowly removing each possible culprit you eventually will have isolated the actual problem.
Answer option B is incorrect. You cannot define a solution if you have not isolated the problem.
Answer option A is incorrect. Once you have isolated the problem, you can then attempt obvious fixes.
Answer option D is incorrect. Alternative solutions should be considered after you have isolated the problem and tried obvious fixes.