Computer Networking Basic Test

1. IPv6 has a size of?

128 bits

64 bits

256

None of the above

IPv6 has a size of 128 bits. This means that an IPv6 address is composed of 128 binary digits, allowing for a significantly larger number of unique addresses compared to IPv4. The increased address space in IPv6 is necessary to accommodate the growing number of devices connected to the internet, ensuring that there are enough unique addresses for each device.

Explanation

IPv6 has a size of 128 bits. This means that an IPv6 address is composed of 128 binary digits, allowing for a significantly larger number of unique addresses compared to IPv4. The increased address space in IPv6 is necessary to accommodate the growing number of devices connected to the internet, ensuring that there are enough unique addresses for each device.

2. In which of the following data can be transferred in two directions?

Duplex

Simplex

Triplex

None of the above

Duplex refers to a communication system in which data can be transferred in two directions simultaneously. This means that both sending and receiving of data can occur at the same time. In contrast, Simplex allows data to be transferred in only one direction, while Triplex is not a valid option for data transfer. Therefore, the correct answer is Duplex.

Explanation

Duplex refers to a communication system in which data can be transferred in two directions simultaneously. This means that both sending and receiving of data can occur at the same time. In contrast, Simplex allows data to be transferred in only one direction, while Triplex is not a valid option for data transfer. Therefore, the correct answer is Duplex.

3. Which of the following wildcard masks is most useful for matching all IP packets in subnet 10.1.128.0, mask 255.255.240.0?

0.0.0.0

0.0.0.31

0.0.0.240

0.0.0.255

0.0.15.255

0.0.15.255 matches all packets with the same ﬁrst 20 bits. This is useful when you want to match a subnet in which the subnet part comprises the ﬁrst 20 bits, as in this case.

Explanation

0.0.15.255 matches all packets with the same ﬁrst 20 bits. This is useful when you want to match a subnet in which the subnet part comprises the ﬁrst 20 bits, as in this case.

4. Which of the following has highest speed?

LAN

WAN

MAN

PAN

LAN stands for Local Area Network, which is a network that covers a small geographical area, typically within a single building or campus. LANs provide high-speed data transfer rates and low latency, making them suitable for applications that require fast communication, such as video streaming or online gaming. WAN (Wide Area Network) covers a larger area, such as multiple buildings or cities, and typically has slower speeds due to the longer distance and more complex infrastructure. MAN (Metropolitan Area Network) is larger than a LAN but smaller than a WAN, and PAN (Personal Area Network) is the smallest, typically covering a person's immediate surroundings. Therefore, LAN has the highest speed among the given options.

Explanation

LAN stands for Local Area Network, which is a network that covers a small geographical area, typically within a single building or campus. LANs provide high-speed data transfer rates and low latency, making them suitable for applications that require fast communication, such as video streaming or online gaming. WAN (Wide Area Network) covers a larger area, such as multiple buildings or cities, and typically has slower speeds due to the longer distance and more complex infrastructure. MAN (Metropolitan Area Network) is larger than a LAN but smaller than a WAN, and PAN (Personal Area Network) is the smallest, typically covering a person's immediate surroundings. Therefore, LAN has the highest speed among the given options.

5. What general guideline should you follow when placing extended IP ACLs?

Perform all ﬁltering on output if at all possible.

Put more-general statements early in the ACL.

Filter packets as close to the source as possible.

Order the ACL commands based on the source IP addresses, lowest to highest, to improve performance.

The authorized Cisco curriculum makes the suggestion in answer C for extended IP ACLs, suggesting that standard ACLs be placed as close to the destination as possible.

Explanation

The authorized Cisco curriculum makes the suggestion in answer C for extended IP ACLs, suggesting that standard ACLs be placed as close to the destination as possible.

6. Which of the following tools requires the end user to telnet to a router to gain access to hosts on the other side of the router?

Named ACLs

Reﬂexive ACLs

Dynamic ACLs

Time-based ACLs

Dynamic ACLs require the user to telnet to the router and authenticate using a username and password, which then causes the router to permit packets sent by the host.

Explanation

Dynamic ACLs require the user to telnet to the router and authenticate using a username and password, which then causes the router to permit packets sent by the host.

7. Which of the following access-list commands permits trafﬁc that matches packets going to any web client from all web servers whose IP addresses begin with 172.16.5?

Access-list 101 permit tcp host 10.1.1.1 172.16.5.0 0.0.0.255 eq www

Access-list 1951 permit ip host 10.1.1.1 172.16.5.0 0.0.0.255 eq www

Access-list 2523 permit tcp any eq www 172.16.5.0 0.0.0.255

Access-list 2523 permit tcp 172.16.5.0 0.0.0.255 eq www 172.16.5.0 0.0.0.255

Access-list 2523 permit tcp 172.16.5.0 0.0.0.255 eq www any

Because the packet is going toward any web client, you need to check for the web server’s port number as a source port. The client IP address range is not speciﬁed in the question, but the servers are, so the source address beginning with 172.16.5 is the correct answer.

Explanation

Because the packet is going toward any web client, you need to check for the web server’s port number as a source port. The client IP address range is not speciﬁed in the question, but the servers are, so the source address beginning with 172.16.5 is the correct answer.

8. Which of the following ﬁelds can be compared using a named extended IP ACL but not a numbered extended IP ACL?

Protocol

Source IP address

Destination IP address

TOS byte

None of the other answers are correct.

Named extended IP ACLs can match the exact same set of ﬁelds as can numbered extended IP ACLs.

Explanation

Named extended IP ACLs can match the exact same set of ﬁelds as can numbered extended IP ACLs.

9. In a router running IOS 12.3, an engineer needs to delete the second line in ACL 101, which currently has four commands conﬁgured. Which of the following options could be used?

Delete the entire ACL and reconﬁgure the three ACL statements that should remain in the ACL.

Delete one line from the ACL using the no access-list... command.

Before IOS 12.3, numbered ACLs must be removed and then reconﬁgured to remove a line from the ACL. As of IOS 12.3, you can also use ACL conﬁguration mode and sequence numbers to delete one ACL line at a time.

Explanation

Before IOS 12.3, numbered ACLs must be removed and then reconﬁgured to remove a line from the ACL. As of IOS 12.3, you can also use ACL conﬁguration mode and sequence numbers to delete one ACL line at a time.

10. Barney is a host with IP address 10.1.1.1 in subnet 10.1.1.0/24. Which of the following
are things that a standard IP ACL could be conﬁgured to do?

Match the exact source IP address

Match IP addresses 10.1.1.1 through 10.1.1.4 with one access-list command without matching other IP addresses

Match all IP addresses in Barney’s subnet with one access-list command without matching other IP addresses

Match only the packet’s destination IP address

Standard ACLs check the source IP address. The address range 10.1.1.1–10.1.1.4 can be matched by an ACL, but it requires multiple access-list commands.
Matching all hosts in Barney’s subnet can be accomplished with the access-list 1 permit 10.1.1.0 0.0.0.255 command.

Explanation

Standard ACLs check the source IP address. The address range 10.1.1.1–10.1.1.4 can be matched by an ACL, but it requires multiple access-list commands.
Matching all hosts in Barney’s subnet can be accomplished with the access-list 1 permit 10.1.1.0 0.0.0.255 command.

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