Unit 11- Networking

You are an application developer and are writing a program to exchange video files through a TCP/IP network. You need to select a transport protocol that will guarantee delivery. Which TCP/IP protocol would you implement that provides this capability?

TCP (Transport Layer = UDP / TCP)

You have a computer that is connected to the Internet through a NAT router. You want to use a private addressing scheme for your computer. Which of the following IP addresses could you assign to the computer? (Select all that apply.)

10.0.12.15 192.168.12.253 172.18.188.67 (10.0.0.0 to 10.255.255.255 172.16.0.0 to 172.31.255.255 192.168.0.0 to 192.168.255.255)

Which of the following configuration files holds the name of the host?

/etc/hostname (host and domain names)

Which of the following files contain information that enables a Linux system to resolve IP addresses to FQDN/host names. (Choose all that apply.)

/etc/hosts /etc/resolv.conf (not /etc/services or /etc/sysconfig/network-scripts/ifup)

If you are managing a systemd-based Linux system, which of the following commands cannot be used to bring the enp2s0 interface down?

/etc/init.d/network stop /etc/sysconfig/network-scripts/ifcfg-enp2s0 down

What is the full path and filename of the file you should edit to determine the order in which name resolution is done? (typed)

/etc/nsswitch.conf

What is the default subnet mask for address 132.44.156.67?

255.255.0.0 (1-126, 128-191, 192-223)

You are configuring the IP address for a host and have been asked to use the address 192.160.99.110/16. What subnet mask value would you use?

255.255.0.0 (8+8+0+0=/16)

What is the path and filename of the file in the Linux system that lists all network services, including the port assigned to the service?

/etc/services

You are troubleshooting a workstation that is having trouble while browsing the Internet. You want to perform some tests on name resolution. Which utility would give you the most information?

dig (more information that nslookup)

The enp2s0 network interface has already been assigned the IP configuration: 172.16.1.123/16. Which command would you use to temporarily configure a second IP address of 192.168.0.123/24 for this network interface?

ip addr add 192.168.0.123/24 dev enp2s0 (ifconfig temp replaces)

Which commands display the IP address and subnet mask values configured on a workstation? (Select two)

ip addr show ifconfig

After an acquisition of another company, you are in a position where you must add another network to the existing routing tables. Which of the following commands would you use to accomplish this? (Select two)

ip route add 11.12.13.14/24 via 201.12.3.4 route add -net 11.12.13.14/24 gw 201.12.3.4 (ip route add= no -net) (rout add= -net for network, not -host)

As a system administrator you need to add a static route so that you can reach host 195.156.76.122 255.255.255.0 and the device eno32 to find the target network. Which commands will work? (Select two)

ip route add 195.156.76.0/24 dev eno32 route add -net 195.156.76.0 netmask 255.255.255.0 dev eno32 (ip route does not use netmask because it uses CIDR) (routeadd needs -net, netmask, and dev)

You need to set an IP address for enp2s0 to 192.168.15.2 with a subnet mask of 255.255.255.0. Which commands are correct? (Select two)

ip addr add 192.168.15.2/24 dev ifconfig enp2s0 192.168.15.2 netmask 255.255.255.0

You have a TCP/IP network with 50 hosts. There have been inconsistent communication problems between hosts. You run a protocol analyzer and discover that two hosts have the same IP address assigned. Which protocol can you implement on your network to help prevent problems such as this?

DHCP

Which network service would you use to get the IP address from the Fully Qualified Domain Name (FQDN) hostname?

DNS (Not NAT, DHCP, FTP)

You want to implement a protocol on your network that allows computers to find the IP address of a host from a logical name. Which protocol should you implement?

DNS (Not Telnet, DHCP, or ARP)

You would like to see how many different computers are currently connected to your local workstation. Which of the following commands would allow you to do this?

netstat (not ping, traceroute)

Which of the following utilities would you use to view the routing table? (Select two)

route ip route show

You have replaced the default gateway on your network. The gateway had used the IP address of 201.12.3.4 and you must remove it from the routing table. Which command would you use to accomplish this?

route del default gw 201.12.3.4 (route add, route del, ip rout add, ip route del)

You are having trouble contacting a host on another network. Ping fails, but you would like to get more information about the router in the path where the communication stops. Which of the following utilities would you use?

traceroute

Which of the following protocols allows hosts to exchange messages to indicate problems with packet delivery?

ICMP (not TCP)

Which of the following are valid IPv6 addresses? Select all that apply.

141:0:0:0:15:0:0:1 6384:1319:7700:7631:446A:5511:8940:2552

Which of the following is a valid IPv6 address?

FEC0::AB:9007 (0-9, A-F, 1 "::")

You have just made IP configuration changes in the ifcfg-enp2sl file. You do not want to restart the Linux system or restart the network service to put these changes into effect. There are two ip commands you can use to put these changes into effect. 1. What is the first ip command you enter at the command line to put these changes into effect? 2. What is the second ip command you enter at the command line to put these changes into effect?

1 ip link set enp2sl down 2 ip link set enp2sl up

Which of the following IP addresses belong to the Class A network 114.0.0.0? (Select three.) Tip: Assume the network is indicated by the default portion of the IP address.

114.0.0.15 114.122.66.12 114.58.12.0 (255.0.0.0)

You check the IP address on a host on the network. The address is 122.16.155.71 with a mask of 255.0.0.0. What is the broadcast address?

122.255.255.255 (Network=122, Host=16.155.71)

Which of the following IP addresses is a valid IP address for a host on a public network?

142.15.6.1 (Private = 10.0.0.0 to 10.255.255.255 172.16.0.0 to 172.31.255.255 192.168.0.0 to 192.168.255.255)

You have a computer that is connected to the Internet through a NAT router. You want to use a private addressing scheme for your computer. Which of the following IP addresses could you assign to the computer? (Select three.)

172.18.188.67 10.0.12.15 192.168.12.253 (10.0.0.0 to 10.255.255.255 172.16.0.0 to 172.31.255.255 192.168.0.0 to 192.168.255.255)

You are the administrator for a small network of Linux hosts. Your network does not communicate with the Internet and does not use DNS. When you add a new host named ENERGY7 to the network, which entry should be added to the /etc/hosts files?

192.168.0.34 ENERGY7 #Reception Area (IP, Name, Description)

What is the network address for the address 199.78.240.240 if the default subnet mask is used?

199.78.240.0 (1-126, 128-191, 192-223)

With a growing concern for security, you convince your boss to stop allowing telnet access to the network. Remote connections will now be allowed only through the use of ssh. Which port must you allow through the firewall for ssh access?

22

You want to maintain tight security on your internal network, so you restrict access to the network through certain port numbers. If you want to allow users to continue to use DNS, which port should you enable?

53

You have just finished configuring a new network card in your Linux system. You would like to verify that it is configured to access the Internet. Which of the following solutions would best help you verify that you have Internet access?

Attempt to ping a site on the Internet. (outside the LAN)

Which TCP/IP configuration parameter identifies the router that is used to reach hosts on remote networks?

Default gateway

Which routing component is used to forward packets to remote networks?

Default gateway

Which of the following describes an IPv6 address? (Select two)

Eight hexadecimal quartets 128-bit address

You are the system administrator of a test lab of computers running Linux. For security reasons your lab is not connected to the corporate network and therefore you are not able to resolve host names via the corporate DNS server. You do, however, want to be able to connect to the lab computers using host names, but you do not have the resources to bring up your own DNS server. Which of the following solutions would satisfy your requirements?

Enter the IP addresses and host names for all of the lab computers in the /etc/hosts file on each of the machines in the lab.

Your ISP has changed the IP addresses of their DNS servers. What would you need to do on your Linux system to still be able to continue resolving host and fully qualified domain names if you use statically assigned IP address information?

Enter the IP addresses of the new DNS servers into the /etc/resolv.conf file. (Not /etc/hosts)

Which of the following correctly describe the most common format for expressing IPv6 addresses? (Select two.)

Hexadecimal numbers 32 numbers, grouped using colons

Which of the following describes link-local IPv6 addresses? (Select 3)

Link-local IPv6 addresses begin with FE8, FE9, FEA, or FEB. Link-local IPv6 addresses are not routable. Link-local IPv6 addresses must be assigned to any network interface on a Linux system.

IPv6 uses 128-bit addresses. The address contains two 64-bit components. What is the first 64-bit component called? What is the last 64-bit component called? (both typed)

Prefix Interface ID

Your computer has an IP address of 161.13.5.15. Your computer is on a

Public network (Private = 10.0.0.0 to 10.255.255.255 172.16.0.0 to 172.31.255.255 192.168.0.0 to 192.168.255.255)

You are attempting to ping another computer on the Internet by its IP address, but you are not getting a response. You do however get a response when pinging a host on your own network. Which of the following commands would help you better determine where the problem is?

Run traceroute on the IP address of the computer on the Internet. (netstat will not help in this scenario)

In which IPv6 configuration method do clients use Neighbor Discovery Protocol to send router solicitation and router advertisement messages as part of the process of automatically generating the interface ID and learning the subnet prefix and default gateway?

Stateless autoconfiguration (Static assignment= manual, DHCPv6= used DHCPv6 server)

You open the /etc/nsswitch.conf file and observe the following line: hosts: files dns What is the result of this configuration?

The /etc/hosts file takes precedence over information obtained from a DNS server when resolving domain names. (getent hosts <host_name> can be used to search host names using nsswitch method)

What would be the result of the following command? *host www.somedom.com*

The IP address of the computer www.somedom.com would be displayed.

You are asked to troubleshoot a problem on a user's computer. When the user types the name of any Web site, he gets a message "The page cannot be displayed". You determine that nothing has changed on the computer. What is the likely problem?

The DNS server is down or not reachable.

Which command could you use to see the path that a packet traveled across a network to a remote host?

Traceroute

After arriving at work in the morning you turn on your Linux workstation and attempt to visit an Internet news site. After a few minutes your Web browser times out telling you that the Web site is unavailable. Which of the following troubleshooting steps would be helpful in determining the problem? (Choose all that apply.)

Use the *ping* command to ping the FQDN and IP address of the Web site you are trying to reach. Use the *traceroute* command to traceroute the FQDN and IP address of the Web site you are trying to reach.

Which of the following commands can be used to retrieve the IP address and/or FQDN/host name information from a DNS server? (Choose all that apply.)

host dig nslookup (not netstat)

What would you enter at the command prompt to find the IP address for the xyzcomp.com domain? (typed)

host xyzcomp.com (Not getent, dig, hostname, or nslookup) (host SINGULAR)

A user calls the help desk to report that she is unable to connect to the network after an upgrade of her Linux operating system. You suspect the problem is related to the network configuration. Which commands could you use to quickly see the current IP address(es) assigned to her computer? (Select two.)

ifconfig -a ip addr show (netstat -a= shows listening sockets)

You need to temporarily change the IP address of the network interface (enp2s0) to 192.168.1.50 where it is currently set to 10.0.1.50. Which of the following commands would achieve the desired result?

ifconfig enp2s0 192.168.1.50

The enp2s0 interface is currently down. What can you enter at the command line to start the enp2s0 interface? (typed)

ifup enp2s0 (or) ip link set enp2s0 up s

Which utility would you use to view current connections and active sessions and ports on a computer?

netstat (current / active)

You are troubleshooting a connectivity problem on a Linux server. You are able to connect to another system local network, but are not able to connect to a server on a remote network. You suspect that the default gateway information for the system may be configured incorrectly. Which of the following commands would you use to view the default gateway information on the Linux server?

netstat -r (-r= routing table/ IP address of default gateway)

Which command displays network activity statistics for TCP, UDP, and IP?

netstat -s (-s = statistics for each protocol)

Which of the following commands would allow you to see if a remote computer is reachable?

ping

As a system administrator you are going to add a static route for host 195.157.66.221 255.255.255.0. Your default gateway is 192.168.5.1 but you want this route to use gateway 192.168.7.1. Which commands will work? (Select two)

route add -net 195.157.66.0 netmask 255.255.255.0 gw 192.168.7.1 ip route add 195.157.66.0/24 via 192.168.7.1

As a system administrator you want to block (reject) any packets from 170.122.0.0 255.255.0.0. Which command will block those packets?

route add 170.122.0.0 netmask 255.255.0.0 reject (not block)

Which utility is similar to traceroute but does not require elevated privileges? (typed)

tracepath

While troubleshooting a problem on a Linux system, you run a utility that generates the following output: 5 s3232.gw.Seat.someisp.net (63.201.72.9) 38.433 ms 38.713 ms 39.085 ms 6 stlll22.garl.Seat.someisp.net (211.242.9.121) 38.620 ms 38.593 ms 38.050 ms 7 oc48-6yy.Seat.someisp.net (14.248.154.129) 57.440 ms 56.678 ms 57.675 ms 8 t223hgh-ytry.swa.someisp.net (142.133.89.232) 103.041 ms 57.181 ms 56.619 ms 9 t8343mmd.cgssel.someisp.net (162.191.10261) 91.977 ms 93.971 ms 93.767 ms 10 twirem2.cgssfdl.ip.someisp.net (145.97.133.23) 92.463 ms 92.337 ms 93.523 ms 11 twerrml.nfffsiny.ip.someisp.net (117.116.141.38) 106.000 ms 106.007 ms 105.283 ms 12 gbed22repp0.n5ddsdsy.ip.someisp.net (123.194.132.8) 103.198 ms 105.447 ms 104.263 ms Which of the following utilities were you using?

traceroute (each router and the time)