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Question 61:
What is a valid IPv6 address format?
A 192.168.1.1
B 2001:0db8:85a3:0000:0000:8a2e:0370:7334
C 255.255.255.255
D 2001:db8::g1e3:2558:9a01
Correct Answer: B
Explanation:
The correct answer is B, which represents a valid IPv6 address in its standard format. IPv6 (Internet Protocol version 6) addresses are composed of eight groups of four hexadecimal digits, with each group separated by a colon. Each group represents 16 bits, and the entire address is 128 bits in length. The 2001:0db8:85a3:0000:0000:8a2e:0370:7334 address is an example of this, following the format and using hexadecimal characters (0-9 and A-F).
One of the key features of IPv6 is its vastly expanded address space compared to IPv4, allowing for a much larger number of unique addresses. With IPv6, there are approximately 340 undecillion addresses available, which ensures that devices worldwide can have unique IPs for the foreseeable future.
An important point to note about IPv6 addresses is that they can be abbreviated to make them easier to write and manage. For example, leading zeros in any block of the address can be dropped, and consecutive blocks of zeros can be represented by a double colon (::), but this can only be done once in an address. Thus, the address 2001:0db8:0000:0000:0000:8a2e:0370:7334 can be shortened to 2001:db8::8a2e:370:7334.
This ability to shorten the address helps reduce human error when writing or configuring devices. IPv6 is essential as the world’s demand for IP addresses continues to grow, and IPv4’s address pool was exhausted.
- A: The address 192.168.1.1 is an example of IPv4, which uses a different addressing scheme. It is a private IP address and is used for local communication within a network.
- C: 255.255.255.255 is a special broadcast address in IPv4, used to send data to all devices within a local network. It is not a valid IPv6 address.
- D: The address 2001:db8::g1e3:2558:9a01 is invalid because it contains the character “g,” which is not allowed in hexadecimal format. Hexadecimal digits must be from 0 to 9 or A to F.
In summary, IPv6 addresses follow a specific structure with hexadecimal digits separated by colons, and 2001:0db8:85a3:0000:0000:8a2e:0370:7334 is an example of a valid IPv6 address.
Question 62:
Which of the following is a key benefit of implementing VLANs in a network?
A Improved security and traffic isolation
B Reduced network traffic
C Increased network complexity
D Automatic IP address assignment
Correct Answer: A
Explanation:
The correct answer is A. Implementing VLANs (Virtual Local Area Networks) in a network offers improved security and traffic isolation. VLANs allow network administrators to logically segment a physical network into multiple smaller, isolated networks. This segmentation is typically done based on functional groups, department divisions, or security levels, allowing the network to function more efficiently and securely.
For example, an organization might have separate VLANs for its finance department and HR department. Even though these departments may exist on the same physical network infrastructure, the VLANs ensure that traffic from one department is logically isolated from the other. This isolation reduces the risk of unauthorized access to sensitive information.
A major benefit of using VLANs is that broadcast traffic is confined within the VLAN. This means that broadcast frames, which can consume network resources and cause unnecessary delays, are restricted to specific VLAN segments. This makes the network more efficient, especially in larger environments with multiple devices, as broadcast traffic will not flood the entire network.
Additionally, VLANs enhance security by creating barriers between different segments. For example, by placing sensitive systems or servers on a dedicated VLAN, an organization can apply specific access controls, such as limiting which users or devices can communicate with those systems.
- B: While VLANs can reduce broadcast traffic within each VLAN, they do not directly reduce overall network traffic. They help segment traffic, but they do not inherently reduce the volume of data being transferred on the network.
- C: Implementing VLANs can simplify network management in many cases. While they add logical complexity to the network, they often reduce the physical complexity by allowing logical segmentation within a shared infrastructure.
- D: The automatic assignment of IP addresses is handled by DHCP (Dynamic Host Configuration Protocol), not VLANs. VLANs do not directly deal with IP address assignment, although each VLAN is typically configured to operate within its own IP address range.
In summary, the main benefit of implementing VLANs is improved security and traffic isolation by dividing the network into smaller, manageable segments.
Question 63:
Which of the following commands is used to configure an IP address on a Cisco router interface?
A ip address [address] [subnet mask]
B interface ip address [address] [subnet mask]
C set interface ip [address] [subnet mask]
D configure ip address [address] [subnet mask]
Correct Answer: A
Explanation:
The correct answer is A. The command to configure an IP address on a Cisco router interface is ip address [address] [subnet mask]. This is used in the interface configuration mode of the Cisco IOS.
To assign an IP address to a router interface, you first need to enter the global configuration mode. Then, select the interface (such as GigabitEthernet0/1 or FastEthernet0/0) and use the ip address command to assign the IP address and subnet mask.
For example:
- Enter global configuration mode:
Router# configure terminal - Access the specific interface:
Router(config)# interface FastEthernet0/0 - Assign the IP address and subnet mask:
Router(config-if)# ip address 192.168.1.1 255.255.255.0 - Bring the interface up with the no shutdown command:
Router(config-if)# no shutdown
Once the IP address is assigned, the interface is ready to communicate with devices on the network. The no shutdown command activates the interface, as interfaces are typically in a shutdown state by default after configuration.
- B: The command interface ip address [address] [subnet mask] is not correct in Cisco IOS syntax.
- C: The set interface ip [address] [subnet mask] command is not valid in Cisco IOS.
- D: configure ip address [address] [subnet mask] is also an invalid Cisco IOS command.
In summary, the ip address [address] [subnet mask] command is the correct syntax used to configure an IP address on a Cisco router interface.
Question 64:
Which of the following layers of the OSI model is responsible for error detection and correction?
A Transport Layer
B Data Link Layer
C Network Layer
D Application Layer
Correct Answer: B
Explanation:
The correct answer is B. The Data Link Layer (Layer 2) of the OSI model is responsible for error detection and correction during data transmission. This layer ensures that data frames are transmitted without errors between devices on the same physical network segment. If an error is detected, it can request that the data be retransmitted.
One of the primary methods used for error detection in the Data Link Layer is Cyclic Redundancy Check (CRC). CRC is a mathematical algorithm that generates a value based on the contents of the data frame. This value is included in the frame’s trailer. When the frame reaches its destination, the receiver performs the same CRC check. If the calculated CRC value matches the value in the frame, the data is considered error-free. If there is a mismatch, it indicates that there has been a transmission error, and the receiver can request the frame to be retransmitted.
In addition to error detection, the Data Link Layer is also responsible for frame synchronization, flow control, and media access control (MAC). These functions ensure that devices can transmit data without colliding with each other on a shared medium.
- A: The Transport Layer (Layer 4) is responsible for providing end-to-end communication and ensuring reliable data transfer across networks. It does not perform error detection in the sense of physical data transmission but does handle reliable delivery.
- C: The Network Layer (Layer 3) deals with routing and forwarding packets between devices across different networks. While it can perform error handling on packets, it does not manage error correction in the same way the Data Link Layer does.
- D: The Application Layer (Layer 7) is concerned with application-level protocols and services like HTTP, FTP, and DNS. It does not involve error detection or correction in the transmission of data.
In summary, the Data Link Layer is responsible for detecting and correcting errors during the transmission of data frames between devices on a local network.
Question 65:
What is the main purpose of a router in a network?
A To forward traffic within a single network
B To assign IP addresses to devices on a network
C To route traffic between different networks
D To prevent unauthorized access to a network
Correct Answer: C
Explanation:
The correct answer is C. The main purpose of a router in a network is to route traffic between different networks. Routers operate at the Network Layer (Layer 3) of the OSI model and use IP addresses to determine the most efficient path for forwarding data packets between different networks. This enables communication between devices on separate networks, such as connecting a local area network (LAN) to the internet.
Routers make forwarding decisions based on their routing tables, which contain information about the best paths to various destination networks. These routing tables are populated either manually, by configuring static routes, or dynamically using routing protocols like RIP, OSPF, or BGP. These protocols help routers exchange information and adjust routing paths based on network changes.
In addition to routing, routers can perform other functions like Network Address Translation (NAT), which helps translate private IP addresses into public IP addresses for internet access. Routers can also have firewall features to filter unwanted traffic and manage security policies.
- A: This describes the role of switches, not routers. Switches operate at the Data Link Layer (Layer 2) and forward traffic within a single network based on MAC addresses.
- B: The assignment of IP addresses is performed by DHCP servers, not routers. While routers can assign IP addresses in some configurations, this is not their main function.
- D: The task of preventing unauthorized access to a network is handled by firewalls and security appliances, not by routers.
In summary, the primary role of a router is to route traffic between different networks, using IP addresses and routing protocols to ensure data reaches its intended destination.
Question 66:
Which of the following protocols is used for dynamically assigning IP addresses to devices on a network?
A DNS
B DHCP
C HTTP
D FTP
Correct Answer: B
Explanation:
The correct answer is B, DHCP (Dynamic Host Configuration Protocol). DHCP is used to dynamically assign IP addresses to devices on a network. When a device such as a computer or smartphone connects to a network, it sends a DHCP request to the DHCP server. The server responds by providing an IP address, subnet mask, default gateway, and other necessary information for the device to communicate on the network.
DHCP simplifies network management by eliminating the need for administrators to manually assign IP addresses to each device. It allows devices to join the network and receive the appropriate IP configuration automatically, ensuring that each device has a unique address.
The DHCP lease typically lasts for a specified period, after which the device must request a new IP address. This is especially useful in large networks with a high number of devices. The server keeps track of which IP addresses are in use and ensures there are no conflicts.
- A: DNS (Domain Name System) is a protocol used to resolve domain names (like www.example.com) into IP addresses. It does not assign IP addresses to devices.
- C: HTTP (Hypertext Transfer Protocol) is used for transferring web pages and resources over the internet. It does not have anything to do with IP address assignment.
- D: FTP (File Transfer Protocol) is used to transfer files between computers over a network. It does not assign IP addresses either.
In summary, DHCP is the protocol responsible for dynamically assigning IP addresses to devices on a network, simplifying network management and ensuring devices can communicate seamlessly.
Question 67:
Which of the following is a characteristic of a switch in a Layer 2 network?
A It routes traffic between different networks.
B It uses MAC addresses to forward data.
C It assigns IP addresses to devices.
D It performs error detection and correction.
Correct Answer: B
Explanation:
The correct answer is B, which describes how a switch in a Layer 2 network uses MAC addresses to forward data. A switch operates at the Data Link Layer (Layer 2) of the OSI model and is responsible for forwarding frames within the same local network (LAN). It uses MAC (Media Access Control) addresses to determine the destination of each frame and forward it to the correct port on the switch.
When a frame is received, the switch examines the source MAC address and records it in a MAC address table. It then uses the destination MAC address to determine the correct port to forward the frame to. If the destination MAC address is not in the table, the switch will flood the frame to all ports except the one it came from, much like a hub.
Switches provide high-speed data forwarding and help reduce collisions by segmenting the network into separate collision domains. This increases network efficiency and reduces network congestion.
- A: This describes the role of a router, not a switch. A router operates at the Network Layer (Layer 3) and is used to route traffic between different networks.
- C: IP address assignment is performed by a DHCP server, not a switch.
- D: Error detection and correction is handled at the Data Link Layer, but switches typically perform basic error detection using CRC to ensure that frames are correctly received. However, they are not responsible for full error correction.
In summary, a switch in a Layer 2 network forwards data based on MAC addresses, facilitating efficient communication within a local network.
Question 68:
What is the purpose of a subnet mask in an IP network?
A To route traffic between different networks
B To determine which part of an IP address is the network and which part is the host
C To assign an IP address to a device
D To prevent unauthorized access to a network
Correct Answer: B
Explanation:
The correct answer is B. The purpose of a subnet mask in an IP network is to determine which part of an IP address represents the network portion and which part represents the host portion. The subnet mask works alongside the IP address to define the structure of a network.
A subnet mask is composed of 32 bits, and it consists of two main parts:
- The network portion: This part of the address is used to identify the network itself.
- The host portion: This part identifies individual devices (hosts) within that network.
For example, a common subnet mask is 255.255.255.0. This means that the first 24 bits (the 255 parts) represent the network address, and the remaining 8 bits (the 0 part) represent the host address within that network.
Subnetting allows you to divide a large network into smaller, more manageable subnetworks, which helps optimize network performance and improve security. By using different subnet masks, network administrators can define how many hosts are available in each subnet and the total number of subnets.
- A: Routing traffic between different networks is the role of a router, not a subnet mask.
- C: IP address assignment is typically handled by a DHCP server or manual configuration, not by the subnet mask.
- D: Preventing unauthorized access is the job of a firewall or other security devices, not the subnet mask.
In summary, the subnet mask helps define the network and host portions of an IP address, allowing for network segmentation and efficient traffic management.
Question 69:
Which type of address is used to uniquely identify devices on a local network?
A IPv6 address
B IPv4 address
C MAC address
D Subnet mask
Correct Answer: C
Explanation:
The correct answer is C, the MAC address. A MAC (Media Access Control) address is a unique identifier assigned to network interfaces for communications at the Data Link Layer (Layer 2) of the OSI model. MAC addresses are assigned to network interfaces by manufacturers and are typically permanent, meaning they do not change.
Each network interface card (NIC) has a unique MAC address, which is used by network devices like switches to forward frames within a local network. The MAC address is 48 bits in length and is typically written in hexadecimal format (e.g., 00:1A:2B:3C:4D:5E).
Unlike IP addresses, which can change depending on the network configuration or the use of DHCP, MAC addresses are fixed and remain constant for the lifetime of the device. They are essential for local communication within a network.
- A: IPv6 addresses are used for communication across networks, not specifically for identifying devices on a local network.
- B: IPv4 addresses are used for network-level addressing and routing, but they are not specific to identifying devices on a local network.
- D: The subnet mask defines the network and host portions of an IP address but does not serve to uniquely identify devices.
In summary, the MAC address is used to uniquely identify devices on a local network for Layer 2 communication.
Question 70:
What is the default administrative distance of OSPF (Open Shortest Path First)?
A 90
B 100
C 110
D 120
Correct Answer: C
Explanation:
The correct answer is C, which is 110. The administrative distance (AD) is a measure of the reliability of a routing protocol. The lower the AD, the more preferred the route is. OSPF (Open Shortest Path First) is a Link-State routing protocol that has a default administrative distance of 110. This means that if a router learns about a route from multiple sources, and one of the routes is advertised by OSPF, it will prefer that route if the other route has a higher administrative distance.
Administrative distance is used by routers to compare routing information from different sources and choose the most reliable route. Each routing protocol has a default administrative distance, and OSPF’s default value of 110 indicates its preference relative to other protocols like RIP (which has an AD of 120) and EIGRP (which has an AD of 90).
- A: 90 is the administrative distance of EIGRP, not OSPF.
- B: 100 is not the correct administrative distance for any of the major routing protocols. OSPF specifically has an administrative distance of 110.
- D: 120 is the administrative distance of RIP (Routing Information Protocol), which is less preferred than OSPF.
In summary, the default administrative distance of OSPF is 110, which determines how much trust is placed in the routes it advertises compared to other routing protocols.
Question 71:
Which protocol is used to find the MAC address of a device based on its IP address in an Ethernet network?
A ICMP
B ARP
C DHCP
D DNS
Correct Answer: B
Explanation:
The correct answer is B, ARP (Address Resolution Protocol). ARP is a protocol used to map IP addresses to MAC addresses in an Ethernet network. When a device wants to communicate with another device on the same local network, it needs to know the MAC address corresponding to the destination device’s IP address.
For example, if a device with IP address 192.168.1.1 wants to send a packet to a device with IP address 192.168.1.2, it first checks its ARP table to see if the MAC address corresponding to 192.168.1.2 is already stored. If it is not, the device will send an ARP request to the network, asking “Who has IP address 192.168.1.2?”. The device with that IP address will reply with its MAC address, allowing the sender to update its ARP table and forward the packet.
ARP is essential for communication within local networks, as Ethernet frames are delivered using MAC addresses, but higher-layer protocols like IP use IP addresses for routing. ARP bridges this gap by translating IP addresses into MAC addresses.
- A: ICMP (Internet Control Message Protocol) is used for diagnostic functions like ping and traceroute, but it does not map IP addresses to MAC addresses.
- C: DHCP (Dynamic Host Configuration Protocol) is used to dynamically assign IP addresses to devices, not to find MAC addresses.
- D: DNS (Domain Name System) resolves domain names (like www.example.com) to IP addresses, but it does not deal with MAC addresses.
In summary, ARP is the protocol used to map IP addresses to MAC addresses, enabling devices on the same network to communicate with each other.
Question 72:
What is the primary function of a router in a network?
A To switch data between devices on the same local network
B To route traffic between different networks
C To assign IP addresses to devices
D To provide power to network devices
Correct Answer: B
Explanation:
The correct answer is B, a router is primarily used to route traffic between different networks. A router operates at Layer 3 (Network Layer) of the OSI model and is responsible for forwarding packets from one network to another. Routers connect different networks, such as local area networks (LANs), wide area networks (WANs), and the internet, and determine the best path for data to travel based on various routing protocols like OSPF, RIP, or EIGRP.
Routers make decisions based on the destination IP address of incoming packets and maintain a routing table to determine the most efficient path to forward packets. When data is destined for a different network, the router encapsulates the data into a new frame, changes the MAC address (if necessary), and forwards it to the next hop on its way to the destination.
- A: This is the role of a switch, which operates at Layer 2 (Data Link Layer) and forwards data between devices on the same local network.
- C: DHCP (Dynamic Host Configuration Protocol) is used to assign IP addresses to devices, not the router.
- D: While some routers may offer Power over Ethernet (PoE) capabilities to provide power to devices like phones and cameras, this is not their primary function. Their main function is routing traffic between different networks.
In summary, routers are responsible for routing traffic between different networks, ensuring that data reaches its destination across various network segments.
Question 73:
What is the primary purpose of the NAT (Network Address Translation) protocol?
A To convert private IP addresses into public IP addresses
B To assign IP addresses dynamically to devices
C To encrypt data between two devices
D To provide a unique MAC address to devices on a network
Correct Answer: A
Explanation:
The correct answer is A, NAT (Network Address Translation). NAT is used to convert private IP addresses into public IP addresses, and vice versa. It is primarily used in situations where a local network uses private IP address ranges (defined by RFC 1918) but needs to access the internet, which requires public IP addresses.
For example, an organization may have multiple devices (computers, printers, etc.) connected to a router, each with a private IP address like 192.168.1.100, but when these devices access the internet, the router uses NAT to translate their private IP addresses into a single public IP address, which is used for all outgoing traffic. This allows multiple devices within the private network to share one public IP address when accessing external services, which helps conserve the limited pool of public IP addresses.
NAT also helps with security by hiding the internal structure of a network from external devices. Since only the router’s public IP address is visible on the internet, internal IP addresses are not exposed.
- B: DHCP (Dynamic Host Configuration Protocol) is used for dynamically assigning IP addresses to devices, but it is not related to the translation of IP addresses.
- C: Encryption is typically handled by protocols such as IPsec or TLS, not NAT.
- D: MAC addresses are used for local communication at the Data Link Layer and are not involved in the translation of IP addresses.
In summary, NAT’s primary purpose is to convert private IP addresses into public IP addresses, allowing devices on a private network to access the internet.
Question 74:
Which of the following is the most commonly used cable type for wired network connections?
A Fiber optic cable
B Coaxial cable
C Twisted pair cable
D HDMI cable
Correct Answer: C
Explanation:
The correct answer is C, twisted pair cable. Twisted pair cable is the most commonly used type of cable for wired network connections. It consists of pairs of wires that are twisted together to reduce electromagnetic interference. There are two main types of twisted pair cables: unshielded twisted pair (UTP) and shielded twisted pair (STP).
UTP cables are the most widely used and are commonly found in Ethernet networks. These cables are used to connect devices such as computers, routers, switches, and other networking equipment. The most common standard for Ethernet is Cat5e and Cat6 cables, which support speeds ranging from 100 Mbps to 10 Gbps over short distances.
Twisted pair cables are preferred for their cost-effectiveness, ease of installation, and flexibility, making them the standard for local area networks (LANs). They are also relatively immune to external interference due to their twisted design, though shielded twisted pair cables can offer further protection against external noise.
- A: Fiber optic cables are used for high-speed, long-distance communication, but they are more expensive and are generally used in backbone infrastructure rather than local connections.
- B: Coaxial cables were used in older network technologies (like 10Base2 Ethernet), but they are not as common in modern networks.
- D: HDMI cables are used for video and audio connections, not for networking.
In summary, twisted pair cables are the most commonly used type of cable for wired network connections, offering a good balance of cost, performance, and ease of use.
Question 75:
Which of the following best describes the function of the data link layer (Layer 2) in the OSI model?
A It provides end-to-end communication between devices.
B It handles error correction and flow control.
C It routes packets between different networks.
D It defines the physical addressing and transmission of data over the medium.
Correct Answer: D
Explanation:
The correct answer is D, the Data Link Layer (Layer 2) is responsible for defining the physical addressing and the transmission of data over the communication medium. The Data Link Layer works directly with the physical medium and provides a reliable link between two directly connected devices by handling tasks such as frame encoding, error detection, and flow control.
At the Data Link Layer, devices like switches and network interface cards (NICs) operate. The primary responsibility of this layer is to create frames that can be transmitted over the physical medium, using MAC addresses to uniquely identify devices on the local network. The Data Link Layer ensures that data is correctly formatted and checks for errors during transmission, such as by using cyclic redundancy check (CRC) to detect errors in received frames.
The Data Link Layer is crucial for communication within a local network, ensuring that data is reliably delivered from one device to another over a specific medium, such as an Ethernet cable or Wi-Fi.
- A: End-to-end communication between devices is the function of the Transport Layer (Layer 4), not the Data Link Layer.
- B: While the Data Link Layer handles error detection, error correction is typically handled by the Transport Layer (Layer 4).
- C: Routing of packets between different networks is the function of the Network Layer (Layer 3), not the Data Link Layer.
In summary, the Data Link Layer is responsible for physical addressing, framing, and error detection, ensuring reliable data transmission over the local network.
Question 76:
What is the primary purpose of the DHCP protocol in a network?
A To assign MAC addresses to devices
B To dynamically assign IP addresses to devices
C To resolve domain names to IP addresses
D To manage the flow of data between devices
Correct Answer: B
Explanation:
The correct answer is B, DHCP (Dynamic Host Configuration Protocol). DHCP is used to dynamically assign IP addresses to devices on a network. It automates the process of IP address allocation, which is particularly useful in large networks where manual IP assignment would be impractical.
When a device (like a computer or smartphone) connects to a network, it sends a DHCP discover message to locate a DHCP server. The server then assigns an available IP address from a pool of addresses and sends it back to the device, along with other essential network configuration information, such as the subnet mask, default gateway, and DNS servers. This process ensures that devices can automatically and efficiently join the network without requiring manual IP configuration.
DHCP reduces the chances of IP address conflicts, ensures that devices have a valid IP configuration, and simplifies network management. In addition, DHCP allows for dynamic IP address assignment, meaning that devices may get a new IP address when they reconnect to the network, which is useful in environments with a large number of devices.
- A: MAC address assignment is not the role of DHCP. MAC addresses are usually assigned by the network interface card (NIC) during the manufacturing process.
- C: DNS (Domain Name System) is used to resolve domain names into IP addresses, not to assign IP addresses.
- D: Managing data flow between devices is done by the Transport Layer (Layer 4) or specific network devices, such as routers and switches.
In summary, DHCP’s primary role is to dynamically assign IP addresses to devices, simplifying network management and improving efficiency.
Question 77:
Which of the following is a key advantage of using VLANs (Virtual Local Area Networks) in a network?
A They increase the physical distance between network devices.
B They allow segmentation of a network into multiple logical networks.
C They improve the network’s routing capabilities.
D They provide higher bandwidth for communication between devices.
Correct Answer: B
Explanation:
The correct answer is B, VLANs (Virtual Local Area Networks) allow for the segmentation of a physical network into multiple logical networks. VLANs create separate broadcast domains within the same physical infrastructure, allowing network administrators to group devices based on function, department, or any other criteria, regardless of their physical location.
By grouping devices into VLANs, network administrators can improve network performance, security, and manageability. For example, devices within the same VLAN can communicate with each other without impacting other devices on the same physical network. Additionally, VLANs help reduce broadcast traffic, as broadcasts are limited to devices within the same VLAN. This makes it easier to control the flow of traffic and isolate sensitive data between different network segments.
Another advantage of VLANs is that they allow for simplified network management by enabling devices in different locations to be part of the same logical network without the need to physically move them. This is particularly beneficial in large organizations or networks with many users across different locations.
- A: VLANs do not directly impact the physical distance between devices; they are used for logical segmentation.
- C: While VLANs can improve network management, they do not directly affect routing capabilities. Routing between VLANs requires a router or Layer 3 switch.
- D: VLANs do not directly increase bandwidth. Bandwidth depends on the underlying physical infrastructure and the type of connections used between devices.
In summary, VLANs allow for the logical segmentation of a network, helping with network management, security, and efficiency by isolating traffic within specific groups of devices.
Question 78:
What does the spanning tree protocol (STP) prevent in a network?
A IP address conflicts
B Routing loops
C MAC address duplication
D Broadcast storms
Correct Answer: D
Explanation:
The correct answer is D, Spanning Tree Protocol (STP) prevents broadcast storms in a network. A broadcast storm occurs when there is a loop in the network, causing frames to circulate endlessly, which can flood the network and consume a significant amount of bandwidth. STP is used to ensure there are no loops in the network by designating one switch port as the root and blocking redundant paths.
In a network with redundant paths, there is a risk that frames might circulate endlessly if there is a loop in the topology. STP prevents this by creating a loop-free topology where only one active path exists between switches at any given time. If the primary path fails, STP will automatically reconfigure the network to use a backup path, ensuring that the network remains operational without causing a broadcast storm.
STP operates by exchanging BPDU (Bridge Protocol Data Units) messages between switches to determine the best path to use and to block redundant paths that could create loops. By preventing loops, STP helps maintain network stability and reduces the risk of broadcast storms.
- A: IP address conflicts are managed by DHCP or manual address assignment, not by STP.
- B: Routing loops are prevented by routing protocols (like OSPF or RIP), not by STP.
- C: MAC address duplication is a concern with network device configuration or addressing, not STP.
In summary, STP prevents broadcast storms by ensuring there are no loops in the network, maintaining the efficiency and stability of the network.
Question 79:
Which of the following is the default administrative distance for EIGRP?
A 90
B 100
C 110
D 120
Correct Answer: A
Explanation:
The correct answer is A, the default administrative distance (AD) for EIGRP (Enhanced Interior Gateway Routing Protocol) is 90. Administrative distance is used by routers to determine the reliability of routing information. The lower the administrative distance, the more preferred the route is.
EIGRP, which is a hybrid routing protocol developed by Cisco, combines features of both distance-vector and link-state protocols. The default administrative distance of 90 makes EIGRP more preferred than other routing protocols like RIP (which has an AD of 120) but less preferred than OSPF (which has an AD of 110).
The administrative distance value helps routers decide which routing information to trust when multiple routes to the same destination are available from different routing protocols. For example, if a router learns about a route from both OSPF and EIGRP, it will prefer the EIGRP route because it has a lower administrative distance.
- B: 100 is not the correct AD for EIGRP. EIGRP’s default AD is 90.
- C: OSPF has an AD of 110, not EIGRP.
- D: RIP has an AD of 120, which is higher than EIGRP’s AD of 90.
In summary, EIGRP has a default administrative distance of 90, making it more preferred than OSPF and RIP when determining the best route.
Question 80:
Which device operates at Layer 3 (Network Layer) of the OSI model and is used to route traffic between different networks?
A Switch
B Hub
C Router
D Bridge
Correct Answer: C
Explanation:
The correct answer is C, Router. A router operates at the Network Layer (Layer 3) of the OSI model and is responsible for routing traffic between different networks. Routers examine the destination IP address of incoming packets and use their routing table to determine the best path for forwarding the packets toward their destination.
Routers are essential for inter-network communication, connecting different subnets or network segments. They also handle traffic management and path selection, ensuring that data is forwarded efficiently across different network types, such as local area networks (LANs), wide area networks (WANs), and the internet.
Routers can be configured to use various routing protocols like OSPF, EIGRP, and RIP to dynamically discover network paths and make routing decisions based on metrics like distance, bandwidth, and link quality. They also support NAT (Network Address Translation) and ACLs (Access Control Lists) for security and traffic control.
- A: A switch operates at Layer 2 (Data Link Layer) and forwards frames based on MAC addresses, not IP addresses.
- B: A hub is a basic device that operates at Layer 1 (Physical Layer) and simply broadcasts data to all connected devices.
- D: A bridge operates at Layer 2 (Data Link Layer) and is used to segment traffic within a network, but it does not route traffic between different networks.
In summary, a router operates at Layer 3 and routes traffic between different networks, making it a critical component of network communication.
