Answers to Review Questions ( Network+ Chapter 3 )

Answers to Review Questions

1. D. Samba is installed on a UNIX server to allow Windows clients to be able to see the UNIX device as a server on the Windows network.

2. D. The NetBEUI/NetBIOS protocol stack does not contain a Network layer routing protocol because it was intended for LAN use only and, as such, cannot be routed.

3. B. The range of the numbers for the first octet in a Class B IP addressing scheme is 128–191. The range of 0–127 is for Class A, 192–223 is for Class C, and 224–255 is reserved for other classes
and purposes.

4. A. The purpose of a subnet mask is to separate the network portion and the host portion of an IP address. In the Internet Protocol addressing scheme, it is a group of selected bits whose values serve to identify a subnet. All members of the subnet share the mask value. Once each portion is identified using the mask, members of each subnet can be referenced more easily.

5. C. Port 80 is the TCP port number used to initiate HTTP connections between web client (browser) and web server. Port 23 is used for Telnet, port 25 is used for SMTP, and port 443 is
used for less common secure web server access using HTTPS.

6. D. The TCP port number used to initiate connections between POP3 clients and servers is 110. As previously mentioned, port 25 is used for SMTP, and port 80 is used for HTTP connections.
Port 100 is not normally used in typical Internet communications.

7. A. FTP clients connect to FTP servers using TCP port 21. As already mentioned, port 25 is used for SMTP, port 80 is used for HTTP, and port 110 is used for POP3 mail communications.

8. B. Internet e-mail servers send mail between themselves using the SMTP protocol. The SNMP protocol is used for the management and monitoring of various network devices. The POP protocol is used to download e-mail from mail servers. Telnet is used for remote terminal emulation.

9. C. 255.255.255.0 is the default subnet mask for a Class C address, 255.0.0.0 is the default for a Class A, 255.255.0.0 is the default for Class B, and 255.255.255.255 is the universal broadcast
address.

10. D. Most often, NAT is used in routers and firewalls to translate between two different IP addresses. 

11. B. All 1s in the host portion of an IP address represent the broadcast address for the corresponding subnet. All 0s in the host portion represent the identification of the network or subnet itself. Not being configured with the IP address of a DNS server or the default gateway will not completely disable network communications.

12. B. Of those listed, the only one that maintains a virtual “connection” is TCP. UDP and NetBEUI are both connectionless, and DDP is AppleTalk’s connectionless Datagram Delivery Protocol.

13. D. An extranet is basically an intranet with limited outside access granted to suppliers and affiliates. The Internet and an internet are far too broad to describe this type of network. Intranets, by definition, do not allow any outside access.

14. B. SMTP initiates connections between servers using TCP port number 25.

15. D. The correct acronym expansion for FQDN is Fully Qualified Domain Name. The FQDN is the complete name of an Internet host (e.g., www.sybex.com) that is used when referencing a host from outside that host’s LAN.

16. D. The refresh value in the SOA record of a zone file indicates how many seconds the secondary DNS server will wait before asking the primary server if the zone file has changed. Increasing this value will cause the secondary server to contain invalid information longer, but decreasing the refresh value, as in option A, by too much will generate unnecessary traffic. Option B would
occur by increasing the minimum TTL value in the SOA record and will simply cause resource records to expire less frequently, also increasing the likelihood that cached information will be
invalid. However, decreasing this value does not necessarily trigger a zone transfer for updated information, as decreasing the refresh value would.

17. A, C. Any time the IP address of a server that needs to be accessible from the Internet changes or is added, the entity responsible for maintaining the authoritative zone file for the domain that the server is on must be contacted to make changes to such records as the A record, the MX record, and the SOA record. Changing cabling or adding devices that do not need to be accessed
by name from the Internet are not situations that require a change to the DNS zone file.

18. D. The proper expansion of FTP is File Transfer Protocol. The abbreviation is more commonly used when referring to file-transferring protocols. There can be several protocols for transferring files between machines and/or networks. For example, FTAM provides file-transfer service for networks that use the OSI reference model, and FTP provides these services for TCP/IP protocols.

19. D. Proxy servers act on behalf of clients to provide Internet access and other Internet services. Generally speaking, however, a proxy server does not convert a nonroutable protocol to a
routable protocol.

20. C. Virtual LANs allow a network to be segmented virtually, inside a network switch, so that several ports are grouped together and function collectively as a network segment, possibly by
departmental or other logical groupings.