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208. c. Commonly used protocols for audio and video communications include H.323 and SIP. H.323 is a suite of different protocols. Technologies such as voice over IP (VoIP) permit people to conduct telephone conversations over networks such as the Internet. Video technologies can be used to hold teleconferences or have “video phone” communications between two individuals. The most popular group chat protocol, IRC is a standard protocol that uses relatively simple text-based communications. IRC also provides a mechanism for users to send and receive files. WEP is a security protocol that encrypts data sent to and from wireless devices within a network. WEP is not as strong as Wi-Fi protected access (WPA) protocol.

209. Which of the following are the primary software components of a domain name system (DNS)?

1. Operating system

2. File system

3. Name server

4. Resolver

a. 1 and 2

b. 1 and 3

c. 2 and 3

d. 3 and 4

209. d. The domain name system (DNS) software primary components include the name server and the resolver. The operating system, file system, and communication stack are part of a DNS hosting environment.

210. Which of the following is the primary type of domain name system (DNS) data?

a. Configuration file

b. Zone file

c. File system

d. Zone transfer

210. b. The primary type of domain name system (DNS) data is zone file, which contains information about various resources in that zone. The information about each resource is represented in a record called a Resource Record (RR). Logically, a zone file is made up of several RR sets.

Configuration file is incorrect because it is a secondary type of DNS data. File system is incorrect because it is a part of the DNS hosting environment. Zone transfer is incorrect because it is a part of DNS transactions.

211. Which of the following configurations is not a good security practice for a single domain name system (DNS) name server to perform?

a. Both authoritative name server and recursive name server

b. Both caching name server and local name server

c. Both primary name server and secondary name server

d. Both master name server and slave name server

211. a. A specific name server can be configured to be both an authoritative and a recursive name server. In this configuration, the same name server provides authoritative information for queries pertaining to authoritative zones while it performs the resolving functions for queries pertaining to other zones. To perform the resolving function, it has to support recursive queries. Any server that supports recursive queries is more vulnerable to attack than a server that does not support such queries. As a result, authoritative information might be compromised. Therefore, it is not a good security practice to configure a single name server to perform both authoritative and recursive functions.

Caching name and local name server are incorrect because a caching name server generally is the local name server in the enterprise that performs the name resolution function on behalf of the various enterprise clients. A caching name server, also called a resolving/recursive name server, provides responses either through a series of queries to authoritative name servers in the hierarchy of domains found in the name resolution query or from a cache of responses built by using previous queries.

Primary, secondary, master, and slave name servers are incorrect because a master (or primary) name server contains zone files created and edited manually by the zone administrator. A slave (or secondary) name server also contains authoritative information for a zone, but its zone file is a replication of the one in the associated master name server. The replication is enabled through a transaction called “zone transfer” that transfers all Resource Records (RRs) from the zone file of a master name server to the slave name server.

212. Which of the following is the most common transaction in a domain name system (DNS)?

a. DNS query/response

b. Zone transfer

c. Dynamic updates

d. DNS NOTIFY message

212. a. Domain name system (DNS) query/response is the most common transaction in DNS. The most common query is a search for a Resource Record (RR), based on its owner name or RR type. The response may consist of a single RR, an RRset, or an appropriate error message.