Book: LPI Linux Certification in a Nutshell Section: Chapter 22. Exam 102 Review Questions and Exercises
### 22.7 Networking Fundamentals (Topic 1.12) #### 22.7.1 Review Questions Describe how the subnet mask affects the maximum number of hosts that can be put on a TCP/IP network. Name the three default address classes and the subnet masks associated with them. The UDP protocol is said to be connectionless. Describe this concept and its consequences on applications that use UDP. What user command is frequently used to send ICMP messages to remote hosts in order to verify those hosts' functionality? Describe the contents and use of /etc/hosts. In what configuration file are DNS servers listed? What is intended if the local loopback address is included there on a workstation? Name two modes of the netstat command and the program's output in each case. Describe why the route command is needed for a single interface on a nonrouting workstation. How does traceroute determine the identities of intermediate gateways? Describe the advantages and consequences of implementing DHCP. What utility is used to configure and dial a modem prior to the creation of a PPP connection? What are the four authentication modes commonly used during PPP negotiations? #### 22.7.2 Exercises Examine your system's TCP/IP configuration using ifconfig eth0 or a similar command for your network interface. Are you using DHCP? What type of subnet are you running with? Is it a Class A, B, or C address? Are you using a private address? Experiment with taking the interface offline using ifconfig eth0 down and ifconfig eth0 up. Examine the contents of /etc/services. Use the dig command to locate information from DNS servers about a domain name. Examine your /etc/hosts file. How much name resolution is accomplished in this file manually? Examine your /etc/resolv.conf file. How many DNS servers do you have available? Execute netstat -r. How many routes are reported? What are the routes to the local network and interface for? Use traceroute to examine the route to a favorite web site. If you are using DHCP, use pump -r to release your IP address, followed by pump -R and pump -s. Does the system still function correctly on the network? Using a standard modem (not a WinModem), use minicom to connect to the modem and verify that it responds to the `AT` command. Execute a manual PPP connection as described in Chapter 19. Does your modem successfully connect to your Internet Service Provider? Examine /var/log/messages for information on the PPP session.