1.
Which of the following are private IP networks?
Correct Answer(s)
A. 172.31.0.0
C. 192.168.255.0
2.
Which of the following is the result of a Boolean AND between IP address 150.150.4.100 and mask 255.255.192.0?
Correct Answer
B. 1001 0110 1001 0110 0000 0000 0000 0000
Explanation
The result of a Boolean AND between the IP address 150.150.4.100 and the mask 255.255.192.0 is obtained by performing a bitwise AND operation between the binary representations of the IP address and the mask. In this case, the mask 255.255.192.0 can be represented in binary as 11111111.11111111.11000000.00000000. When performing the bitwise AND operation, any bit that has a corresponding 1 in both the IP address and the mask will result in a 1, while any bit that has a corresponding 0 in either the IP address or the mask will result in a 0. Therefore, the bits that are common between the IP address and the mask will remain the same, while the bits that are different will be set to 0. Thus, the correct answer is 1001 0110 1001 0110 0000 0000 0000 0000.
3.
Which of the following shows the equivalent of subnet mask 255.255.248.0, but in prefix notation?
Correct Answer
D. /21
Explanation
The subnet mask 255.255.248.0 has a total of 21 network bits. In prefix notation, the equivalent is represented by /21. This means that the first 21 bits of the IP address are used to identify the network, while the remaining bits are used to identify hosts within that network.
4.
If mask 255.255.255.128 were used with a Class B network, how many subnets could exist, with how many hosts per subnet, respectively?
Correct Answer
E. 512 and 126
Explanation
If a Class B network is being used with a subnet mask of 255.255.255.128, it means that the last octet of the IP address is divided into two parts: the first 7 bits are used for the network portion, and the last bit is used for the host portion.
Since there are 7 bits in the host portion, the number of possible subnets is 2^7, which equals 128. However, the first and last subnets are reserved, so the actual number of usable subnets is 128-2, which equals 126.
On the other hand, since there is only 1 bit in the host portion, the number of possible hosts per subnet is 2^1, which equals 2. However, the first and last addresses in each subnet are reserved (network address and broadcast address), so the actual number of usable hosts per subnet is 2-2, which equals 0.
Therefore, the correct answer is 512 and 126.
5.
A Class B network needs to be subnetted such that it supports 100 subnets and 100 hosts/subnet. For this design, if multiple masks meet those design requirements, the engineer should choose the mask that maximizes the number of hosts per subnet. Which of the following masks meets the design criteria?
Correct Answer
B. /23
Explanation
The /23 subnet mask meets the design criteria because it allows for 510 hosts per subnet, which is more than the required 100 hosts per subnet. The other options do not provide enough hosts per subnet to meet the design requirements.
6.
If mask 255.255.255.240 were used with a Class C network, how many subnets could exist, with how many hosts per subnet, respectively?
Correct Answer
C. 16 and 14
Explanation
With a subnet mask of 255.255.255.240, a Class C network can be divided into 16 subnets, each with 14 hosts. This is because the subnet mask 255.255.255.240 allows for 4 bits to be used for subnetting, which gives us 2^4 = 16 subnets. Each subnet can have 2^4 - 2 = 14 hosts, as 2 addresses are reserved for network address and broadcast address in each subnet. Therefore, the correct answer is 16 and 14.
7.
Which of the following subnet masks lets a Class B network have up to 150 hosts per subnet, and supports 164 subnets?
Correct Answer
C. 255.255.255.0
Explanation
The subnet mask 255.255.255.0 allows a Class B network to have up to 150 hosts per subnet and supports 164 subnets. This is because the subnet mask 255.255.255.0 has 8 bits available for host addresses, which can accommodate 2^8 - 2 = 254 hosts per subnet. Since we need to have up to 150 hosts per subnet, this subnet mask meets the requirement. Additionally, the subnet mask has 8 bits available for network addresses, which can support 2^8 = 256 subnets. Since we need to support 164 subnets, this subnet mask also meets that requirement.
8.
Which of the following subnet masks let a Class A network have up to 150 hosts per subnet and supports 164 subnets?
Correct Answer(s)
B. 255.255.0.0
C. 255.255.255.0
D. 255.255.192.0
E. 255.255.252.0
Explanation
Each subnet mask represents the number of bits used to identify the network and host portions of an IP address. In this case, a Class A network has a default subnet mask of 255.0.0.0, which provides 8 bits for the network portion and 24 bits for the host portion. To have up to 150 hosts per subnet, we need at least 8 bits for the host portion, so the subnet mask must be at least 255.255.0.0. Additionally, to support 164 subnets, we need at least 8 bits for the network portion, so the subnet mask must be at least 255.255.255.0. The other options do not meet these requirements.
9.
Which of the following IP addresses are not in the same subnet as 190.4.80.80, mask 255.255.255.0?
Correct Answer(s)
D. 190.4.90.1
E. 10.1.1.1
Explanation
The given IP addresses 190.4.90.1 and 10.1.1.1 are not in the same subnet as 190.4.80.80 with a mask of 255.255.255.0. This is because the subnet mask of 255.255.255.0 allows for a range of IP addresses from 190.4.80.1 to 190.4.80.254. Therefore, any IP address outside of this range, such as 190.4.90.1 and 10.1.1.1, would not be in the same subnet.
10.
Which of the following IP addresses is not in the same subnet as 190.4.80.80, mask 255.255.240.0?
Correct Answer
E. 10.1.1.1
Explanation
The given IP address 10.1.1.1 is not in the same subnet as 190.4.80.80 with a subnet mask of 255.255.240.0. This is because the subnet mask divides the IP address into network and host portions. In this case, the subnet mask allows for a range of IP addresses from 190.4.80.0 to 190.4.95.255. However, the IP address 10.1.1.1 falls outside of this range and is therefore not in the same subnet.
11.
Which of the following IP addresses are not in the same subnet as 190.4.80.80/25?
Correct Answer(s)
B. 190.4.80.200
C. 190.4.90.1
D. 10.1.1.1
Explanation
The given IP address 190.4.80.80/25 has a subnet mask of 255.255.255.128. This means that the first 25 bits of the IP address are the network address, and the remaining 7 bits are for host addresses.
- 190.4.80.100: This IP address is in the same subnet as 190.4.80.80 because the first 25 bits are the same.
- 190.4.80.200: This IP address is not in the same subnet as 190.4.80.80 because the 7th bit is different.
- 190.4.90.1: This IP address is not in the same subnet as 190.4.80.80 because the first 16 bits are different.
- 10.1.1.1: This IP address is not in the same subnet as 190.4.80.80 because it belongs to a different IP address range.
- 190.4.80.50: This IP address is in the same subnet as 190.4.80.80 because the first 25 bits are the same.
12.
Each of the following answers lists a dotted decimal number and a subnet mask. The dotted decimal number might be a valid IP address that can be used by a host or it might be a subnet number or broadcast address. Which of the answers show an address that can be used by a host?
Correct Answer(s)
B. 192.168.5.160, 255.255.255.192
D. 172.20.49.0, 255.255.254.0
Explanation
The answer 192.168.5.160, 255.255.255.192 and 172.20.49.0, 255.255.254.0 show addresses that can be used by a host. These addresses have subnet masks that allow for host addresses within their respective networks. The subnet masks 255.255.255.192 and 255.255.254.0 provide a sufficient number of host addresses within their network ranges.
13.
Which of the following are valid subnet numbers in network 180.1.0.0 when using mask 255.255.248.0?
Correct Answer(s)
A. 180.1.8.0
B. 180.1.16.0
C. 180.1.32.0
E. 180.1.40.0
Explanation
The given subnet mask is 255.255.248.0. This means that the first 21 bits of the IP address are fixed, and the remaining 11 bits can be used for subnetting. The valid subnet numbers are those that have all 11 bits set to 0 in the subnet portion.
Among the given options, 180.1.8.0, 180.1.16.0, 180.1.32.0, and 180.1.40.0 have all 11 bits set to 0 in the subnet portion, making them valid subnet numbers. However, 180.1.4.0 does not have all 11 bits set to 0 in the subnet portion, so it is not a valid subnet number.
14.
Which of the following are not valid subnet numbers in network 180.1.0.0 when using mask 255.255.255.0?
Correct Answer
A. 180.2.2.0
15.
Which of the following installation steps are typically required on a Cisco router, but not typically required on a Cisco switch?
Correct Answer(s)
B. Connect serial cables
E. Turn the on/off switch to “on”
Explanation
Typically, connecting serial cables and turning the on/off switch to "on" are steps that are required on a Cisco router but not on a Cisco switch. This is because routers often require serial connections for WAN connectivity, while switches primarily rely on Ethernet connections for local network connectivity. Additionally, switches are usually powered on automatically when connected to a power source, whereas routers may have an on/off switch that needs to be manually turned on.
16.
Which of the following roles does a SOHO router typically play in regards to IP address assignment?
Correct Answer(s)
B. DHCP server on the interface connected to the PCs at the home/office
C. DHCP client on the interface connected to the ISP
Explanation
A SOHO router typically acts as a DHCP server on the interface connected to the PCs at the home/office, which means it assigns IP addresses to the devices within the local network. Additionally, it also acts as a DHCP client on the interface connected to the ISP, which means it obtains an IP address from the ISP's network for the router itself to establish an internet connection. This allows the devices in the local network to communicate with each other and access the internet through the router.
17.
Which of the following features would you typically expect to be associated with the router CLI, but not with the switch CLI?
Correct Answer
A. The clock rate command
Explanation
The clock rate command is typically associated with the router CLI, but not with the switch CLI. This command is used to set the clock rate on a serial interface of a router, which is essential for establishing a synchronous connection with another device. Switches do not have serial interfaces, so they do not require the clock rate command.
18.
You just bought two Cisco routers for use in a lab, connecting each router to a different LAN switch with their Fa0/0 interfaces. You also connected the two routers’ serial interfaces using a back-to-back cable. Which of the following steps is not required to be able to forward IP on both routers’ interfaces?
Correct Answer(s)
B. Configuring the bandwidth command on one router’s serial interface
D. Setting the interface description on both the FastEthernet and serial interface of each router
Explanation
The step that is not required to be able to forward IP on both routers' interfaces is configuring the bandwidth command on one router's serial interface. The bandwidth command is used to manually set the bandwidth value on an interface, which is typically used for routing protocols to calculate metrics. However, it is not necessary for forwarding IP traffic on the interfaces. Additionally, setting the interface description on both the FastEthernet and serial interface of each router is also not required for forwarding IP traffic, as interface descriptions are used for administrative purposes and do not affect the forwarding of IP packets.
19.
The output of the show ip interface brief command on R1 lists interface status codes of “down” and “down” for interface Serial 0/0. Which of the following could be true?
Correct Answer
C. R1’s serial interface does not have a serial cable installed.
Explanation
The output of "down" and "down" status codes for the Serial 0/0 interface indicates that the interface is not operational. This could be because there is no serial cable installed in the interface, which prevents it from establishing a connection with the other device.
20.
Which of the following commands does not list the IP address and mask of at least one interface?
Correct Answer(s)
C. Show ip interface brief
E. Show version
Explanation
The command "show ip interface brief" lists the IP address and mask of at least one interface, so it does not fit the criteria. Similarly, the command "show version" also does not list the IP address and mask of any interface.
21.
Which of the following is different on the Cisco switch CLI as compared with the Cisco router CLI?
Correct Answer(s)
B. The number of IP addresses configured
C. The types of questions asked in setup mode
Explanation
The Cisco switch CLI and Cisco router CLI differ in terms of the number of IP addresses configured and the types of questions asked in setup mode. In the switch CLI, the number of IP addresses configured is usually limited to management IP addresses for remote access and network management purposes. On the other hand, in the router CLI, multiple IP addresses can be configured on different interfaces for routing purposes. Additionally, the types of questions asked in setup mode may vary between the switch and router CLI, as they have different functionalities and configurations.
22.
Which of the following could cause a router to change the IOS that is loaded when the router boots?
Correct Answer(s)
D. Boot system configuration command
E. Configuration register
Explanation
The boot system configuration command is used to specify the IOS image that should be loaded during the boot process. By changing this command, the router can be instructed to load a different IOS image. The configuration register is a 16-bit value that determines how the router boots up. By changing the configuration register, the router can be configured to boot from a different location, which may result in a different IOS image being loaded.
23.
Which of the following hexadecimal values in the last nibble of the configuration register would cause a router to not look in Flash memory for an IOS?
Correct Answer
A. 0
Explanation
A router will not look in Flash memory for an IOS when the hexadecimal value in the last nibble of the configuration register is 0.