CCNA Practice 2 (Ch 3-5)

Private IP addressing was specified in RFC __________.

1918 (These addresses can be used on a private network, but they're not routable through the Internet.)

If an Ethernet port on a router were assigned an IP address of 172.16.112.1/25, what would be the valid subnet address of this interface? A. 172.16.112.0 B. 172.16.0.0 C. 172.16.96.0 D. 172.16.255.0 E. 172.16.128.0

A (A /25 mask is 255.255.255.128. Used with a Class B network, the third and fourth octets are used for subnetting with a total of 9 subnet bits, 8 bits in the third octet and 1 bit in the fourth octet. Since there is only 1 bit in the fourth octet, the bit is either off or on—which is a value of 0 or 128. The host in the question is in the 0 subnet, which has a broadcast address of 127 since 112.128 is the next subnet.)

Using the following illustration, what would be the IP address of E0 if you were using the eighth subnet? The network ID is 192.168.10.0/28 and you need to use the last available IP address in the range. The zero subnet should not be considered valid for this question. A. 192.168.10.142 B. 192.168.10.66 C. 192.168.100.254 D. 192.168.10.143 E. 192.168.10.126

A (A /28 is a 255.255.255.240 mask. Let's count to the ninth subnet (we need to find the broadcast address of the eighth subnet, so we need to count to the ninth subnet). Starting at 16 (remember, the question stated that we will not use subnet zero, so we start at 16, not 0), 16, 32, 48, 64, 80, 96, 112, 128, 144 etc.. The eighth subnet is 128 and the next subnet is 144, so our broadcast address of the 128 subnet is 143. This makes the host range 129-142. 142 is the last valid host.)

You have an interface on a router with the IP address of 192.168.192.10/29. What is the broadcast address the hosts will use on this LAN? A. 192.168.192.15 B. 192.168.192.31 C. 192.168.192.63 D. 192.168.192.127 E. 192.168.192.255

A (A /29 (255.255.255.248) has a block size of 8 in the fourth octet. This means the subnets are 0, 8, 16, 24, etc. 10 is in the 8 subnet. The next subnet is 16, so 15 is the broadcast address.)

You have an interface on a router with the IP address of 192.168.192.10/29. Including the router interface, how many hosts can have IP addresses on the LAN attached to the router interface? A. 6 B. 8 C. 30 D. 62 E. 126

A (A /29 (255.255.255.248), regardless of the class of address, has only 3 host bits. Six hosts are the maximum number of hosts on this LAN, including the router interface.)

If you use either Telnet or FTP, what layer are you using to generate the data? A. Application B. Presentation C. Session D. Transport

A (Both FTP and Telnet use TCP at the Transport layer; however, they both are Application layer protocols, so the Application layer is the best answer for this question.)

Which of the following troubleshooting steps, if completed successfully, also confirms the other steps will succeed as well? A. ping a remote computer B. ping the loopback address C. ping the NIC D. ping the default gateway

A (Pinging the remote computer would fail if any of the other tests fail.)

What command displays the ARP table on a Cisco router? A. show ip arp B. traceroute C. arp -a D. tracert

A (The command that displays the ARP table on a Cisco router is show ip arp.)

What network service is the most likely problem if you can ping a computer by IP address but not by name? A. DNS B. DHCP C. ARP D. ICMP

A (The most likely problem if you can ping a computer by IP address but not by name is a failure of DNS.)

Which of the following describe the DHCP Discover message? (Choose two.) A. It uses FF:FF:FF:FF:FF:FF as a layer 2 broadcast. B. It uses UDP as the Transport layer protocol. C. It uses TCP as the Transport layer protocol. D. It does not use a layer 2 destination address.

A, B (A client that sends out a DHCP Discover message in order to receive an IP address sends out a broadcast at both layer 2 and layer 3. The layer 2 broadcast is all Fs in hex, or FF:FF:FF:FF:FF:FF. The layer 3 broadcast is 255.255.255.255, which means any networks and all hosts. DHCP is connectionless, which means it uses User Datagram Protocol (UDP) at the Transport layer, also called the Host-to-host layer.)

Which of the following are layers in the TCP/IP model? (Choose three.) A. Application B. Session C. Transport D. Internet E. Data Link F. Physical

A, C, D (The listed answers are from the OSI model and the question asked about the TCP/IP protocol stack (DoD model). Yes, it is normal for the objectives to have this type of question. However, let's just look for what is wrong. First, the Session layer is not in the TCP/IP model; neither are the Data Link and Physical layers. This leaves us with the Transport layer (Host-to-host in the DoD model), Internet layer (Network layer in the OSI), and Application layer (Application/Process in the DoD). Remember, the CCENT objectives can list the layers as OSI layers or DoD layer at any time, regardless of what the question is asking.)

What protocol is used to find the hardware address of a local device? A. RARP B. ARP C. IP D. ICMP E. BootP

B (Address Resolution Protocol (ARP) is used to find the hardware address from a known IP address.)

Which layer 4 protocol is used for a Telnet connection? A. IP B. TCP C. TCP/IP D. UDP E. ICMP

B (Although Telnet does use TCP and IP (TCP/IP), the question specifically asks about layer 4, and IP works at layer 3. Telnet uses TCP at layer 4.)

Which of the following Application layer protocols sets up a secure session that's similar to Telnet? A. FTP B. SSH C. DNS D. DHCP

B (Secure Shell (SSH) protocol sets up a secure session that's similar to Telnet over a standard TCP/IP connection and is employed for doing things like logging into systems, running programs on remote systems, and moving files from one system to another.)

What layer in the TCP/IP stack is equivalent to the Transport layer of the OSI model? A. Application B. Host-to-Host C. Internet D. Network Access

B (The four layers of the TCP/IP stack (also called the DoD model) are Application/ Process, Host-to-host, Internet, and Network Access. The Host-to-host layer is equivalent to the Transport layer of the OSI model.)

Which of the following commands displays the networks traversed on a path to a network destination? A. ping B. traceroute C. pingroute D. pathroute

B (The traceroute command displays the networks traversed on a path to a network destination.)

If Host A is configured with an incorrect default gateway and all other computers and the router are known to be configured correctly, which of the following statements is TRUE? A. Host A cannot communicate with the router. B. Host A can communicate with other hosts in the same subnet. C. Host A can communicate with hosts in other subnets. D. Host A can communicate with no other systems.

B (With an incorrect gateway, Host A will not be able to communicate with the router or beyond the router but will be able to communicate within the subnet.)

You need to subnet a network that has 5 subnets, each with at least 16 hosts. Which classful subnet mask would you use? A. 255.255.255.192 B. 255.255.255.224 C. 255.255.255.240 D. 255.255.255.248

B (You need 5 subnets, each with at least 16 hosts. The mask 255.255.255.240 provides 16 subnets with 14 hosts—this will not work. The mask 255.255.255.224 provides 8 subnets, each with 30 hosts. This is the best answer.)

Which statements are true regarding ICMP packets? (Choose two). A. ICMP guarantees datagram delivery. B. ICMP can provide hosts with information about network problems. C. ICMP is encapsulated within IP datagrams. D. ICMP is encapsulated within UDP datagrams.

B, C (ICMP is used for diagnostics and destination unreachable messages. ICMP is encapsulated within IP datagrams, and because it is used for diagnostics, it will provide hosts with information about network problems.)

Which of the following services use TCP? (Choose three.) A. DHCP B. SMTP C. SNMP D. FTP E. HTTP F. TFTP

B, D, E (SMTP, FTP, and HTTP use TCP.)

Which two statements describe the IP address 10.16.3.65/23? (Choose two.) A. The subnet address is 10.16.3.0 255.255.254.0. B. The lowest host address in the subnet is 10.16.2.1 255.255.254.0. C. The last valid host address in the subnet is 10.16.2.254 255.255.254.0. D. The broadcast address of the subnet is 10.16.3.255 255.255.254.0. E. The network is not subnetted.

B,D (The mask 255.255.254.0 (/23) used with a Class A address means that there are 15 subnet bits and 9 host bits. The block size in the third octet is 2 (256 - 254). So this makes the subnets in the interesting octet 0, 2, 4, 6, etc., all the way to 254. The host 10.16.3.65 is in the 2.0 subnet. The next subnet is 4.0, so the broadcast address for the 2.0 subnet is 3.255. The valid host addresses are 2.1 through 3.254.)

What is the subnetwork number of a host with an IP address of 172.16.66.0/21? A. 172.16.36.0 B. 172.16.48.0 C. 172.16.64.0 D. 172.16.0.0

C (A /21 is 255.255.248.0, which means we have a block size of 8 in the third octet, so we just count by 8 until we reach 66. The subnet in this question is 64.0. The next subnet is 72.0, so the broadcast address of the 64 subnet is 71.255.)

Using the illustration from the previous question, what would be the IP address of S0 if you were using the first subnet? The network ID is 192.168.10.0/28 and you need to use the last available IP address in the range. Again, the zero subnet should not be considered valid for this question. A. 192.168.10.24 B. 192.168.10.62 C. 192.168.10.30 D. 192.168.10.127

C (A /28 is a 255.255.255.240 mask. The first subnet is 16 (remember that the question stated not to use subnet zero) and the next subnet is 32, so our broadcast address is 31. This makes our host range 17-30. 30 is the last valid host.)

You need to configure a server that is on the subnet 192.168.19.24/29. The router has the first available host address. Which of the following should you assign to the server? A. 192.168.19.0 255.255.255.0 B. 192.168.19.33 255.255.255.240 C. 192.168.19.26 255.255.255.248 D. 192.168.19.31 255.255.255.248 E. 192.168.19.34 255.255.255.240

C (A /29 is 255.255.255.248, which is a block size of 8 in the fourth octet. The subnets are 0, 8, 16, 24, 32, 40, etc. 192.168.19.24 is the 24 subnet, and since 32 is the next subnet, the broadcast address for the 24 subnet is 31. 192.168.19.26 is the only correct answer.)

Which class of IP address provides a maximum of only 254 host addresses per network ID? A. Class A B. Class B C. Class C D. Class D E. Class E

C (A Class C network address has only 8 bits for defining hosts: 28 - 2 = 256.)

Which of the following mechanisms is used by the client to avoid a duplicate IP address during the DHCP process? A. ping B. traceroute C. gratuitous arp D. pathping

C (A host uses something called a gratuitous ARP to help avoid a possible duplicate address. The DHCP client sends an ARP broadcast out on the local LAN or VLAN using its newly assigned address to solve conflicts before they occur.)

Which Class of IP addresses uses the pattern shown below? A. Class A B. Class B C. Class C D. Class D

C (Class C addresses devote 24 bits to the network portion and 8 bits to the host portion.)

You configure a router interface with the IP address 192.168.10.62 255.255.255.192 and receive the following error: Bad mask /26 for address 192.168.10.62 Why did you receive this error? A. You typed this mask on a WAN link and that is not allowed. B. This is not a valid host and subnet mask combination. C. ip subnet-zero is not enabled on the router. D. The router does not support IP.

C (First, you cannot answer this question if you can't subnet. The 192.168.10.62 with a mask of 255.255.255.192 is a block size of 64 in the fourth octet. The host 192.168.10.62 is in the zero subnet, and the error occurred because ip subnet-zero is not enabled on the router.)

The following illustration shows a data structure header. What protocol is this header from? A. IP B. ICMP C. TCP D. UDP E. ARP F. RARP

C (First, you should know easily that only TCP and UDP work at the Transport layer, so now you have a 50/50 shot. However, since the header has sequencing, acknowledgment, and window numbers, the answer can only be TCP.)

What must happen if a DHCP IP conflict occurs? A. Proxy ARP will fix the issue. B. The client uses a gratuitous ARP to fix the issue. C. The administrator must fix the conflict by hand at the DHCP server. D. The DHCP server will reassign new IP addresses to both computers.

C (If a DHCP conflict is detected, either by the server sending a ping and getting a response or by a host using a gratuitous ARP (arp'ing for its own IP address and seeing if a host responds), then the server will hold that address and not use it again until it is fixed by an administrator.)

Which of the following is the best summarization of the following networks: 192.168.128.0 through 192.168.159.0 A. 192.168.0.0/24 B. 192.168.128.0/16 C. 192.168.128.0/19 D. 192.168.128.0/20

C (If you start at 192.168.128.0 and go through 192.168.159.0, you can see this is a block of 32 in the third octet. Since the network address is always the first one in the range, the summary address is 192.168.128.0. What mask provides a block of 32 in the third octet? The answer is 255.255.224.0, or /19.)

What switch must be added to the ipconfig command on a PC to verify DNS configuration? A. /dns B. -dns C. /all D. showall

C (The /all switch must be added to the ipconfig command on a PC to verify DNS configuration.)

In the diagram below what is the most likely reason the station cannot ping outside of its network? A. The IP address is incorrect on E0 of the router. B. The default gateway address is incorrect on the station. C. The IP address on the station is incorrect. D. The router is malfunctioning.

C (The IP address of the station and the gateway are not in the same network. Since the address of the gateway is correct on the station, it is most likely the IP address of the station is incorrect.)

The DoD model (also called the TCP/IP stack) has four layers. Which layer of the DoD model is equivalent to the Network layer of the OSI model? A. Application B. Host-to-Host C. Internet D. Network Access

C (The four layers of the DoD model are Application/Process, Host-to-Host, Internet, and Network Access. The Internet layer is equivalent to the Network layer of the OSI model.)

Which of the following network addresses correctly summarizes the three networks shown below efficiently? 10.0.0.0/16 10.1.0.0/16 10.2.0.0/16 A. 10.0.0.0/15 B. 10.1.0.0/8 C. 10.0.0.0/14 D. 10.0.0.8/16

C (The interesting octet in this example is the second octet, and it is a block size of four starting at 10.0.0.0. By using a 255.252.0.0 mask, we are telling the summary to use a block size of four in the 2nd octet. This will cover 10.0.0.0 through 10.3.255.255. This is the best answer.)

What command generated the output shown below? Reply from 172.16.10.2: bytes=32 time<1ms TTL=128 Reply from 172.16.10.2: bytes=32 time<1ms TTL=128 Reply from 172.16.10.2: bytes=32 time<1ms TTL=128 Reply from 172.16.10.2: bytes=32 time<1ms TTL=128 A. traceroute B. show ip route C. ping D. pathping

C (The ping command tests connectivity to another station. The full command is shown below.) C:\>ping 172.16.10.2 Pinging 172.16.10.2 with 32 bytes of data: Reply from 172.16.10.2: bytes=32 time<1ms TTL=128 Reply from 172.16.10.2: bytes=32 time<1ms TTL=128 Reply from 172.16.10.2: bytes=32 time<1ms TTL=128 Reply from 172.16.10.2: bytes=32 time<1ms TTL=128 Ping statistics for 172.16.10.2: Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms

What is the address range of a Class B network address in binary? A. 01xxxxxx B. 0xxxxxxx C. 10xxxxxx D. 110xxxxx

C (The range of a Class B network address is 128-191. This makes our binary range 10xxxxxx.)

Which of the following is an example of a multicast address? A. 10.6.9.1 B. 192.168.10.6 C. 224.0.0.10 D. 172.16.9.5

C (The range of multicast addresses starts with 224.0.0.0 and goes through 239.255.255.255.)

What is the subnetwork address for a host with the IP address 200.10.5.68/28? A. 200.10.5.56 B. 200.10.5.32 C. 200.10.5.64 D. 200.10.5.0

C (This is a pretty simple question. A /28 is 255.255.255.240, which means that our block size is 16 in the fourth octet. 0, 16, 32, 48, 64, 80, etc. The host is in the 64 subnet.)

To test the IP stack on your local host, which IP address would you ping? A. 172.0.0.1 B. 1.0.0.127 C. 127.0.0.1 D. 127.255.255.255 E. 255.255.255.255

C (To test the local stack on your host, ping the loopback interface of 127.0.0.1.)

To use VLSM, what capability must the routing protocols in use possess? A. Support for multicast B. Multiprotocol support C. Transmission of subnet mask information D. Support for unequal load balancing

C (To use VLSM, the routing protocols in use possess the capability to transmit subnet mask information.)

In the network shown in the diagram, how many computers could be in subnet B? A. 6 B. 12 C. 14 D. 30

C (Using a /28 mask, there are 4 bits available for hosts. Two to the fourth power minus 2 = 14.)

When a ping to the local host IP address fails, what can you assume? A. The IP address of the local host is incorrect. B. The IP address of the remote host is incorrect. C. The NIC is not functional. D. The IP stack has failed to initialize.

C (When a ping to the local host IP address fails, you can assume the NIC is not functional.)

When a ping to the local host IP address succeeds but a ping to the default gateway IP address fails, what can you rule out? (Choose all that apply.) A. The IP address of the local host is incorrect. B. The IP address of the gateway is incorrect. C. The NIC is not functional. D. The IP stack has failed to initialize.

C, D (If a ping to the local host succeeds, you can rule out IP stack or NIC failure.)

Which two of the following are private IP addresses? A. 12.0.0.1 B. 168.172.19.39 C. 172.20.14.36 D. 172.33.194.30 E. 192.168.24.43

C, E (The Class A private address range is 10.0.0.0 through 10.255.255.255. The Class B private address range is 172.16.0.0 through 172.31.255.255, and the Class C private address range is 192.168.0.0 through 192.168.255.255.)

What is the maximum number of IP addresses that can be assigned to hosts on a local subnet that uses the 255.255.255.224 subnet mask? A. 14 B. 15 C. 16 D. 30 E. 31 F. 62

D (A /27 (255.255.255.224) is 3 bits on and 5 bits off. This provides 8 subnets, each with 30 hosts. Does it matter if this mask is used with a Class A, B, or C network address? Not at all. The number of host bits would never change.)

If a host on a network has the address 172.16.45.14/30, what is the subnetwork this host belongs to? A. 172.16.45.0 B. 172.16.45.4 C. 172.16.45.8 D. 172.16.45.12 E. 172.16.45.16

D (A /30, regardless of the class of address, has a 252 in the fourth octet. This means we have a block size of 4 and our subnets are 0, 4, 8, 12, 16, etc. Address 14 is obviously in the 12 subnet.)

You have a network that needs 29 subnets while maximizing the number of host addresses available on each subnet. How many bits must you borrow from the host field to provide the correct subnet mask? A. 2 B. 3 C. 4 D. 5 E. 6 F. 7

D (A 240 mask is 4 subnet bits and provides 16 subnets, each with 14 hosts. We need more subnets, so let's add subnet bits. One more subnet bit would be a 248 mask. This provides 5 subnet bits (32 subnets) with 3 host bits (6 hosts per subnet). This is the best answer.)

On a VLSM network, which mask should you use on point-to-point WAN links in order to reduce the waste of IP addresses? A. /27 B. /28 C. /29 D. /30 E. /31

D (A point-to-point link uses only two hosts. A /30, or 255.255.255.252, mask provides two hosts per subnet.)

Which mask should you use on point-to-point WAN links in order to reduce the waste of IP addresses? A. /27 B. /28 C. /29 D. /30 E. /31

D (A point-to-point link uses only two hosts. A /30, or 255.255.255.252, mask provides two hosts per subnet.)

In the diagram below, in order to have as efficient IP addressing as possible, which network should use a /29 mask? A. A B. B C. C D. D

D (For 6 hosts we need to leave 3 bits in the host portion since 2 to the third power = 8 and 8 less 2 is 6.With 3 bits for the host portion, that leaves 29 bits for the mask or /29.)

What summary address would cover all the networks shown and advertise a single, efficient route to Router B that won't advertise more networks than needed? A. 172.16.0.0/24 B. 172.16.1.0/24 C. 172.16.0.0/24 D. 172.16.0.0/20 E. 172.16.16.0/28 F. 172.16.0.0/27

D (In a question like this, you need to look for an interesting octet where you can combine networks. In this example, the third octet has all our subnets so we just need to find our block size now. If we used a block of 8 starting at 172.16.0.0/19, then we cover 172.16.0.0 through 172.16.7.255. However, if we used 172.16.0.0/20, then we'd cover a block of 16 which would be from 172.16.0.0 through 172.16.15.255, which is the best answer.)

When you issue the ping command, what protocol are you using? A. DNS B. DHCP C. ARP D. ICMP

D (When you issue the ping command, you are using the ICMP protocol.)

Your router has the following IP address on Ethernet0: 172.16.2.1/23. Which of the following can be valid host IDs on the LAN interface attached to the router? (Choose two.) A. 172.16.0.5 B. 172.16.1.100 C. 172.16.1.198 D. 172.16.2.255 E. 172.16.3.0 F. 172.16.3.255

D,E (The router's IP address on the E0 interface is 172.16.2.1/23, which is 255.255.254.0. This makes the third octet a block size of 2. The router's interface is in the 2.0 subnet, and the broadcast address is 3.255 because the next subnet is 4.0. The valid host range is 2.1 through 3.254. The router is using the first valid host address in the range.)

Which of the networks in the diagram could use a /29 mask? A. Corporate B. LA C. SF D. NY E. none

E (A /29 mask yields only 6 addresses, so none of the networks could use it.)

You have a network with a subnet of 172.16.17.0/22. Which is the valid host address? A. 172.16.17.1 255.255.255.252 B. 172.16.0.1 255.255.240.0 C. 172.16.20.1 255.255.254.0 D. 172.16.16.1 255.255.255.240 E. 172.16.18.255 255.255.252.0 F. 172.16.0.1 255.255.255.0

E (A Class B network ID with a /22 mask is 255.255.252.0, with a block size of 4 in the third octet. The network address in the question is in subnet 172.16.16.0 with a broadcast address of 172.16.19.255. Only option E has the correct subnet mask listed, and 172.16.18.255 is a valid host.)

Which configuration command must be in effect to allow the use of 8 subnets if the Class C subnet mask is 255.255.255.224? A. Router(config)#ip classless B. Router(config)#ip version 6 C. Router(config)#no ip classful D. Router(config)#ip unnumbered E. Router(config)#ip subnet-zero F. Router(config)#ip all-nets

E (A Class C subnet mask of 255.255.255.224 is 3 bits on and 5 bits off (11100000) and provides 8 subnets, each with 30 hosts. However, if the command ip subnet-zero is not used, then only 6 subnets would be available for use.)

The network address of 172.16.0.0/19 provides how many subnets and hosts? A. 7 subnets, 30 hosts each B. 7 subnets, 2,046 hosts each C. 7 subnets, 8,190 hosts each D. 8 subnets, 30 hosts each E. 8 subnets, 2,046 hosts each F. 8 subnets, 8,190 hosts each

F (A CIDR address of /19 is 255.255.224.0. This is a Class B address, so that is only 3 subnet bits, but it provides 13 host bits, or 8 subnets, each with 8,190 hosts.)