SUSE Linux Enterprise Server Administration (Course 3037) 7-1

SUSE Linux Enterprise Server Administration (Course 3037) 1-4188-3731-8

Chapter 7 Answers

Review Questions

1. What must each computer have in order to participate on a TCP/IP network as well as contact hosts on remote networks by name? (Choose all that apply.) a. IP address b. netmask c. DNS server d. default gateway ANSWER: a,b,c,d

2. How long is the host ID by default in a Class A network? e. 1 byte f. 2 bytes g. 3 bytes h. 4 bytes ANSWER: c

3. Which of the following are Class B IP addresses? (Choose all that apply.) i. 192.168.1.1 j. 177.16.41.10 k. 127.0.0.1 l. 133.1.1.2 ANSWER: b,d

4. What network address is reserved for loopback? _____ SUSE Linux Enterprise Server Administration (Course 3037) 7-2

ANSWER: 127.0.0.1

5. What name is used to identify the first Ethernet network interface in Linux? _____

ANSWER: eth0

6. What file stores the list of DNS servers that your computer can contact to resolve hostnames into IP addresses? m. /etc/resolv.conf n. /etc/sysconfig/network/scripts o. /etc/dns.sysconfig p. /etc/sysconfig/network/ifcfg-dns ANSWER: a

7. What command can you use to configure the IP address 192.168.1.1 and default subnet mask on your first Ethernet network interface? _____

ANSWER: ipconfig eth0 192.168.1.1

8. What command can you use to configure an additional IP address of 192.168.1.2 and default subnet mask on the same network interface configured in Question 7? _____

ANSWER: ipconfig eth0:1 192.168.1.2

9. Which of the following commands may be used to view IP configuration? (Choose all that apply.) q. ifshow eth0 r. ip address show s. ifconfig -a t. ifstatus eth0 ANSWER: b,c,d

10. What file contains the information used to configure your second Ethernet network interface at boot time? _____ SUSE Linux Enterprise Server Administration (Course 3037) 7-3

ANSWER: /etc/sysconfig/network/scripts/ifcfg-eth-id-hardwareaddress

11. What line would you configure in the file described in Question 10 to obtain an IP configuration from a DHCP server? _____

ANSWER: BOOTPROTO=”dhcp”

12. How many DNS servers may be listed in /etc/resolv.conf? u. one v. three w. ten x. unlimited ANSWER: b

13. Which two commands could you type at a command prompt to add a route to the 188.16.0.0 network via the router 192.168.1.254? y. ip route add 188.16.0.0/16 via 192.168.1.254 z. route add 188.16.0.0 via 192.168.1.254 aa. ip route add gw 192.168.1.254 via 188.16.0.0/16 bb. route add –net 188.16.0.0 netmask 255.255.0.0 gw 192.168.1.254 ANSWER: a,d

14. Which file could you use to configure the static route configured in Question 13 for use with all network interfaces on your system? _____

ANSWER: /etc/sysconfig/network/routes

15. What command could you use send 5 ICMP echo requests to the host 192.168.1.254? _____

ANSWER: ping –c 5 192.168.1.254

16. What command could you use to listen to all traffic sent to port 1433 on your computer? _____ ANSWER: netcat –v –l –p 1433 SUSE Linux Enterprise Server Administration (Course 3037) 7-4

17. What option(s) to the netstat command could you use to display the routing table? _____

ANSWER: -r (or –rn)

18. What command could you use to listen to all packets received on your first Ethernet network inteface? _____ ANSWER: tcpdump

Discovery Exercises

Network Interface Commands a. ifconfig eth0 10.10.10.x b. ifconfig (or ip address show) c. ifdown eth0; ifup eth0 (or ifconfig eth0 down; ifconfig eth0 up) d. ifconfig (or ip address show), /etc/sysconfig/network/ifcfg-eth-id-MACaddress

Configuring IP Aliases a. ifconfig eth0:1 10.10.10.x b. ifconfig (or ip address show) c. ping IP_address d. ifdown eth0; ifup eth0 (or ifconfig eth0 down; ifconfig eth0 up)

Routing Commands e. route add –net 42.0.0.0 netmask 255.0.0.0 gw 10.18.11.88 f. ip route add 43.0.0.0/8 via 10.68.1.9 g. route (or ip route show or netstat –r) h. route del –net 42.0.0.0 netmask 255.0.0.0; route del –net 43.0.0.0 netmast 255.0.0.0 (or ip route del 42.0.0.0/8; ip route del 43.0.0.0/8)