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Question 21. Which of the following IP addresses is most likely to be assigned to a network’s private local area network (LAN)?
A)8.8.8
B) 172.16.0.1
C) 192.0.2.1
D) 224.0.0.1
Answer: B)
Explanation:
A private IP address is used for internal communication within a network and is not routable on the public Internet. The private address ranges for IPv4 are defined by RFC 1918 and fall within specific address blocks. The address range 172.16.0.0 to 172.31.255.255 falls under Class B private addresses, which is what makes 172.16.0.1 a typical private IP address. These private IP addresses are used for internal communication and are commonly assigned to devices such as computers, routers, and printers within a local area network (LAN).
Option A, 8.8.8.8, is a public IP address owned by Google and is used for their public DNS service. This is not a private IP address.
Option C, 192.0.2.1, is a reserved IP address used for documentation and examples (according to RFC 5737) and cannot be used for actual communication in a network.
Option D, 224.0.0.1, is a multicast address used for routing data to a group of devices rather than a single one, so it is not a private address for a LAN.
Private IP addresses allow networks to have internal addresses that are not exposed to the Internet, which is essential for security and efficiency when dealing with multiple devices that need to share a single public IP address (through NAT—Network Address Translation).
Question 22. Which of the following protocols is used to provide secure remote access to a network?
A) FTP
B) SNMP
C) SSH
D) Telnet
Answer: C)
Explanation:
SSH (Secure Shell) is a protocol used to provide secure remote access to devices on a network, such as routers, switches, or servers. It encrypts the communication between the client and the server, ensuring confidentiality and integrity of the transmitted data. SSH operates on port 22 and is the most secure alternative to older protocols like Telnet.
Option A, FTP (File Transfer Protocol), is used to transfer files over a network but does not provide secure communication. FTP transmits data in plain text, which makes it vulnerable to eavesdropping and attacks.
Option B, SNMP (Simple Network Management Protocol), is used for network management and monitoring devices but does not provide secure access for managing devices remotely.
Option D, Telnet, is an older protocol used for remote communication but does not offer encryption. Telnet transmits data in plaintext, making it insecure and vulnerable to interception, especially for sensitive network configurations.
SSH is a critical protocol for secure management of network devices, as it ensures that sensitive data (like passwords and configuration settings) is not exposed during remote sessions.
Question 23. What type of routing protocol does OSPF use?
A) Distance Vector
B) Link-State
C) Hybrid
D) Path Vector
Answer: B)
Explanation:
OSPF (Open Shortest Path First) is a link-state routing protocol. In link-state routing, each router shares its view of the network with all other routers within the same area. OSPF routers maintain a map of the network (called the LSDB, or Link-State Database) and calculate the best paths using the Dijkstra algorithm to determine the shortest path to each network. Link-state protocols like OSPF provide faster convergence and more accurate network topology updates compared to distance-vector protocols.
Option A, Distance Vector, refers to protocols like RIP (Routing Information Protocol) that rely on the exchange of distance and direction information to determine the best paths. This method is slower to converge and prone to routing loops.
Option C, Hybrid, refers to protocols like EIGRP (Enhanced Interior Gateway Routing Protocol), which combines features of both distance-vector and link-state protocols but is not the type used by OSPF.
Option D, Path Vector, is a type of protocol used in BGP (Border Gateway Protocol), which is used for routing between different autonomous systems (ASes) on the Internet.
OSPF is preferred in large enterprise networks because of its scalability, efficiency, and faster convergence compared to distance-vector protocols.
Question 24. Which device in a network operates at the Data Link layer (Layer 2) of the OSI model and uses MAC addresses to forward frames?
A) Router
B) Switch
C) Hub
D) Gateway
Answer: B)
Explanation:
A switch operates at the Data Link layer (Layer 2) of the OSI model. Switches use MAC addresses (Media Access Control addresses) to forward Ethernet frames to their correct destination. Unlike hubs, which simply broadcast data to all connected devices, switches learn the MAC addresses of devices connected to each of their ports and forward traffic only to the port that corresponds to the destination MAC address. This improves network efficiency and reduces unnecessary traffic.
Option A, a router, operates at the Network layer (Layer 3) and forwards packets based on their IP addresses. Routers are used to interconnect different networks and route traffic between them.
Option C, a hub, operates at the Physical layer (Layer 1) and is a basic network device that simply forwards electrical signals to all connected devices without distinguishing between MAC addresses.
Option D, a gateway, is used to connect two different network architectures or protocols and typically operates at higher layers of the OSI model, like the Application layer (Layer 7).
Switches play a critical role in modern Ethernet-based networks by ensuring efficient communication between devices on the same local network (LAN).
Question 25. What is the default subnet mask for an IPv4 Class C address?
A)0.0.0
B) 255.255.0.0
C) 255.255.255.0
D) 255.255.255.255
Answer: C)
Explanation:
The default subnet mask for a Class C IPv4 address is 255.255.255.0. This subnet mask allows for 256 IP addresses, with 254 usable addresses for hosts. Class C addresses are typically used for small to medium-sized networks, and the 255.255.255.0 subnet mask means that the first three octets of the IP address are used for the network portion, while the last octet is used for the host portion.
Option A, 255.0.0.0, is the default subnet mask for Class A addresses. This subnet mask allows for large networks with over 16 million possible host addresses.
Option B, 255.255.0.0, is the default subnet mask for Class B addresses, allowing for networks with up to 65,536 host addresses.
Option D, 255.255.255.255, is used for broadcast addresses and is not a typical subnet mask for any class of IP addresses.
Class C addresses, with the 255.255.255.0 subnet mask, are the most commonly used for small office and home networks, where a relatively small number of devices need to be connected to the same local network.
Question 26. In IPv6, what is the main function of a link-local address?
A) To enable global communication
B) To identify the device on a specific local network segment
C) To support private addressing within a network
D) To provide a routable address for Internet communication
Answer: B)
Explanation:
A link-local address in IPv6 is an address that is used for communication between devices on the same local network segment or link. These addresses are not intended to be routed beyond the local network segment. In fact, link-local addresses are non-routable and are strictly confined to the local network, ensuring that devices can communicate with each other even without requiring a globally routable IP address.
Link-local addresses are automatically assigned to every IPv6-enabled interface when a device connects to a network. They are essential for several important IPv6 operations, such as neighbor discovery (used to identify and verify neighboring devices) and address autoconfiguration (which allows devices to assign themselves an IP address without requiring a DHCP server). These addresses always begin with the prefix FE80::/10, and they are followed by a 64-bit interface identifier, which typically consists of the device’s MAC address or another unique identifier generated for the interface.
Option A is incorrect because link-local addresses are not used for global communication. Instead, global unicast addresses are used for communication that occurs over the Internet or across different networks. Global unicast addresses are routable globally, whereas link-local addresses are designed only for communication within the same network segment or link.
Option C is incorrect because private addressing is not the main function of link-local addresses. In IPv6, Unique Local Addresses (ULA) are used for private addressing, similar to the role of private IPv4 addresses (such as 10.0.0.0/8 or 192.168.0.0/16). Unique Local Addresses are routable within a specific organization or between trusted networks, but they are not routable on the global Internet. Link-local addresses, however, are only valid within a single link and are not used for private addressing or inter-network communication.
Option D is incorrect because link-local addresses cannot be routed on the Internet. These addresses are strictly confined to the local network and are used for functions like neighbor discovery, address resolution, and local communication between devices. If a device needs to communicate with devices outside of the local network, it would need to use a global unicast address or another type of routable IPv6 address.
In summary, link-local addresses are crucial for IPv6 operation because they allow devices on the same local network to communicate and perform essential tasks like neighbor discovery and autoconfiguration. Their non-routable nature ensures that they are strictly used for local communication, and they are automatically configured for each IPv6-enabled device, helping to maintain efficient and flexible networking in IPv6 environments.
Question 27. Which of the following statements about IPv6 addresses is correct?
A) IPv6 addresses are 32 bits long.
B) IPv6 addresses use a decimal format.
C) IPv6 addresses are expressed in hexadecimal format.
D) IPv6 addresses are based on 32-bit blocks.
Answer: C)
Explanation:
IPv6 addresses are 128 bits long, which allows for a vastly larger address space compared to IPv4, which only uses 32 bits. IPv6 addresses are expressed in hexadecimal format, as hexadecimal is a more compact and easier way to represent large binary numbers. Each address consists of eight groups of four hexadecimal digits, separated by colons. Each group represents 16 bits, making the entire address 128 bits in total. For example, a typical IPv6 address might look like this:
2001:0db8:85a3:0000:0000:8a2e:0370:7334
In this example, each group of four hexadecimal digits (e.g., 2001, 0db8, 85a3) corresponds to 16 bits of the address, and the full address consists of eight groups (each 16 bits long), totaling 128 bits. Hexadecimal is used because it is much more efficient for representing large binary numbers, with one hexadecimal digit representing 4 binary bits. This makes IPv6 addresses easier to write and read compared to their full 128-bit binary equivalent.
Option A is incorrect because IPv6 addresses are 128 bits long, not 32 bits. IPv4 addresses, on the other hand, are 32 bits long, which limits the number of possible addresses. IPv6’s 128-bit address space allows for an immense increase in the number of available addresses, making it possible to assign a unique IP address to virtually every device on the planet, with far more to spare.
Option B is incorrect because IPv6 addresses use hexadecimal notation to represent the 128-bit address space, not decimal. While decimal is commonly used in IPv4 addresses (e.g., 192.168.1.1), IPv6 addresses are expressed in hexadecimal for efficiency. Each group of four hexadecimal digits corresponds to 16 bits (or two bytes) of the address, and each hexadecimal digit represents four binary bits.
Option D is incorrect because IPv6 addresses are expressed in 8 blocks of 16 bits each, not 32 bits. The standard format for an IPv6 address is eight groups of four hexadecimal digits, each representing 16 bits (2 bytes). In contrast, IPv4 addresses consist of four octets (8 bits each) separated by periods, making the total length of an IPv4 address 32 bits.
The 128-bit address space of IPv6 enables the allocation of an enormous number of unique IP addresses, far exceeding the number of addresses available with IPv4. While IPv4’s 32-bit address space allows for approximately 4.3 billion unique addresses, IPv6’s 128-bit address space allows for an almost incomprehensible 340 undecillion addresses (3.4 x 10^38), providing ample room for every device, and then some, to have a unique address.
Question 28. In a Cisco router, what is the default administrative distance (AD) for OSPF?
A) 90
B) 110
C) 120
D) 150
Answer: B)
Explanation:
The administrative distance (AD) is a value used by routers to determine the trustworthiness of a routing protocol. It is an integer value that ranges from 0 to 255, where a lower AD indicates a more preferred routing protocol. Routers use AD to decide which routing protocol to trust when multiple protocols provide routes to the same destination. When a router receives routing updates from different protocols, it will choose the route from the protocol with the lowest AD.
For example, in the case of OSPF (Open Shortest Path First), the default AD is 110. This means that if the router receives routing information for the same network from both OSPF and another protocol (such as RIP or EIGRP), it will prefer the OSPF route over those with a higher AD, because 110 is a relatively low value compared to other protocols.
Option A is incorrect because 90 is the default AD for EIGRP (Enhanced Interior Gateway Routing Protocol), not OSPF. EIGRP, which is a Cisco-proprietary protocol, has a lower AD than OSPF (90 versus 110), which means if EIGRP and OSPF provide routes to the same destination, the router will prefer the EIGRP route over the OSPF route. While both OSPF and EIGRP are used in enterprise environments, EIGRP typically has a more favorable AD compared to OSPF.
Option C is incorrect because 120 is the AD for RIP (Routing Information Protocol), which is a distance-vector protocol. RIP’s AD of 120 is higher than OSPF’s 110, meaning that if a router receives routing updates for the same destination from both RIP and OSPF, it will prefer the OSPF route. RIP is an older protocol that is slower to converge and less efficient compared to link-state protocols like OSPF, which is why its AD is higher.
Option D is incorrect because 150 is not a standard AD for any common Cisco routing protocol. The typical AD values for common routing protocols are as follows:
0: Directly connected routes (always preferred)
1: iBGP (internal BGP)
90: EIGRP
110: OSPF
120: RIP
200: External BGP (eBGP)
255: A route that is unreachable (used for routes marked as invalid)
As you can see, 150 does not correspond to any standard routing protocol in Cisco’s typical AD table.
OSPF (Open Shortest Path First) is a widely used link-state routing protocol, commonly found in enterprise networks. It is favored for its scalability and faster convergence compared to distance-vector protocols like RIP. The AD of 110 reflects its moderate preference in comparison to EIGRP (which has an AD of 90) but still places it ahead of RIP, which has a higher AD of 120.
In summary, OSPF’s default administrative distance of 110 ensures that it is preferred over protocols like RIP (AD 120) but less preferred than EIGRP (AD 90) when the router receives routing updates for the same network from different routing protocols.
Question 29. What does NAT (Network Address Translation) do in a network?
A) It allows private IP addresses to be routed on the Internet.
B) It assigns IP addresses to network devices automatically.
C) It translates domain names to IP addresses.
D) It allows multiple devices in a private network to share a single public IP address.
Answer: D)
Explanation:
NAT (Network Address Translation) is a technique used to enable multiple devices in a private network to share a single public IP address when accessing the Internet. This is particularly important in IPv4 environments, where the number of available public IP addresses is limited. NAT helps conserve public IP addresses by allowing many devices within a local network to communicate with external networks using just one or a few public IP addresses.
When a device in the private network sends a request to the Internet, the NAT router modifies the source IP address in the outgoing packet to its own public IP address. This process is known as “source NAT”. The router also keeps track of this connection in a translation table so that when the external server responds, the NAT device can map the response back to the correct private IP address. This allows the internal device to receive the response, even though its IP address is not directly visible on the public network.
For example, if a computer with a private IP address (such as 192.168.1.10) sends a request, the router will replace the source IP address with its own public IP address, say 203.0.113.5. The router then keeps track of the mapping in its NAT table. When the response comes back, the router uses the NAT table to forward it to 192.168.1.10.
Option A is incorrect because NAT does not allow private IP addresses to be routed directly on the Internet. Instead, it hides private IP addresses behind a public IP address when making outbound connections. The router performing NAT changes the private source IP address to the public IP address for packets that go out, but private IP addresses (e.g., 192.168.x.x, 10.x.x.x) cannot be routed on the Internet by themselves. They are only valid within the internal network, and NAT ensures that external servers see the router’s public IP address instead.
Option B is incorrect because IP address assignment is the role of protocols like DHCP (Dynamic Host Configuration Protocol), not NAT. DHCP is responsible for automatically assigning private IP addresses to devices within a local network, whereas NAT is used to manipulate the addresses of outbound and inbound traffic, allowing devices within the private network to access the Internet using a single public IP address. While NAT works in conjunction with DHCP in many networks, they serve different purposes.
Option C is incorrect because DNS (Domain Name System) is responsible for translating domain names into IP addresses, but it is not involved in address translation for outbound or inbound packets like NAT is. DNS helps users access websites by resolving human-readable names into machine-readable IP addresses. NAT, on the other hand, deals with the translation of IP addresses in packets for devices inside a private network to communicate with the outside world.
In summary, NAT is a crucial technology for efficient IP address management and security in networks, particularly in IPv4 environments, where the available address space is limited. It helps conserve public IP addresses and improves security by masking internal IP addresses from the public Internet, making it difficult for external attackers to directly target devices in the private network.
Question 30. Which of the following is the most common type of VLAN used in Ethernet networks?
A) Management VLAN
B) Data VLAN
C) Voice VLAN
D) Default VLAN
Answer: B)
Explanation:
The most common type of VLAN (Virtual Local Area Network) in Ethernet networks is the Data VLAN. A Data VLAN is typically used to carry general network traffic for end devices, such as computers, printers, and other workstations. It allows network administrators to logically segment the network, improving performance and security by isolating broadcast traffic within specific groups.
Option A, Management VLAN, is used specifically for network management traffic. It isolates management traffic from other types of traffic, improving security and access control for network devices.
Option C, Voice VLAN, is used to prioritize voice traffic, ensuring Quality of Service (QoS) for real-time applications like VoIP (Voice over IP).
Option D, Default VLAN, is VLAN 1 by default on many switches, and it often carries management and control traffic, but it is not typically used for general data traffic.
Data VLANs are the workhorse of most networks and provide the basic network segmentation necessary for organizing devices into different logical groups, improving network performance and security.
Question 31. Which layer of the OSI model is responsible for providing end-to-end communication between hosts, including segmentation and reassembly of data?
A) Physical
B) Transport
C) Network
D) Data Link
Answer: B)
Explanation:
The Transport layer (Layer 4) of the OSI model is responsible for providing end-to-end communication services between hosts. It ensures that data is reliably transferred between devices over a network by segmenting large data chunks into smaller packets and reassembling them on the receiving end. The transport layer is also responsible for error detection and correction (through protocols like TCP and UDP), as well as flow control to prevent network congestion.
Option A, Physical, is responsible for the actual transmission of raw bit streams over a physical medium, such as electrical signals or light pulses, and does not handle end-to-end communication.
Option C, Network, is responsible for determining the best path for data across multiple networks and devices, typically using routing protocols, but it does not segment or reassemble data.
Option D, Data Link, ensures the reliable transfer of data frames between directly connected devices, handling MAC addresses and frame synchronization, but it does not provide end-to-end communication across a network.
The Transport layer ensures that data flows smoothly between devices, providing a reliable and error-free communication channel across the network.
Question 32. What is the function of DHCP (Dynamic Host Configuration Protocol) in a network?
A) It assigns static IP addresses to devices.
B) It provides a secure channel for encrypted communication.
C) It dynamically assigns IP addresses to devices.
D) It routes data between different subnets.
Answer: C)
Explanation:
DHCP (Dynamic Host Configuration Protocol) is used to automatically assign IP addresses to devices on a network. It helps network administrators by simplifying the process of IP address management. DHCP assigns dynamic IP addresses to devices (such as computers, printers, and smartphones) when they connect to the network. This process involves a four-step exchange: Discover, Offer, Request, and Acknowledge (DORA).
Option A, static IP addresses, are manually assigned to devices and remain fixed, unlike DHCP, which assigns addresses dynamically.
Option B, secure communication, is typically handled by protocols like SSL/TLS or IPsec, not DHCP.
Option D, routing is the function of a router or routing protocol like OSPF or BGP, not DHCP.
DHCP simplifies network management by automatically allocating IP addresses and ensuring no conflicts, making it essential for modern networks.
Question 33. Which of the following IP address ranges is reserved for private IP addresses according to RFC 1918?
A)0.0.0 – 10.255.255.255
B) 172.32.0.0 – 172.47.255.255
C) 192.168.0.0 – 192.168.255.255
D) 169.254.0.0 – 169.254.255.255
Answer: A)
Explanation:
According to RFC 1918, the following IP address ranges are reserved for private IP addresses:
10.0.0.0 – 10.255.255.255 (Class A)
172.16.0.0 – 172.31.255.255 (Class B)
192.168.0.0 – 192.168.255.255 (Class C)
These address ranges are used for private internal networks and are not routable over the Internet. Devices within a private network can communicate with each other using these private addresses but must use Network Address Translation (NAT) to communicate with external systems.
Option B, 172.32.0.0 – 172.47.255.255, is incorrect because 172.16.0.0 – 172.31.255.255 is the correct range for Class B private addresses.
Option C, 192.168.0.0 – 192.168.255.255, is a correct private address range for Class C networks, but it is not the only correct range—10.0.0.0 – 10.255.255.255 is also valid for private IP addresses.
Option D, 169.254.0.0 – 169.254.255.255, is the range for link-local addresses in IPv4, which are used when a device cannot obtain an IP address from a DHCP server.
Private IP addresses are commonly used in enterprise and home networks to conserve public IP address space and ensure security through NAT.
Question 34. What does the VTP (VLAN Trunking Protocol) allow administrators to do in a Cisco network?
A) Automatically assign IP addresses to devices on different VLANs.
B) Prevent VLANs from being propagated across trunk links.
C) Dynamically propagate VLAN configuration information across switches.
D) Securely encrypt data flowing between switches.
Answer: C)
Explanation:
VTP (VLAN Trunking Protocol) is a Cisco proprietary protocol that allows network administrators to dynamically propagate VLAN configuration information across switches in a network. This means when a VLAN is created, modified, or deleted on one switch, VTP automatically updates the other switches in the domain with the new VLAN information. This simplifies VLAN management, particularly in larger networks with multiple switches.
Option A, assigning IP addresses, is the role of DHCP, not VTP.
Option B, preventing VLAN propagation, is not a function of VTP. In fact, VTP’s purpose is to propagate VLAN information across switches.
Option D, encrypting data, is a task for security protocols like IPsec or SSL, not VTP.
VTP enhances the scalability and manageability of VLANs in large network environments, ensuring consistent VLAN configuration across all switches in the network.
Question 35. What is the default administrative distance (AD) of RIP (Routing Information Protocol)?
A) 90
B) 110
C) 120
D) 150
Answer: C)
Explanation:
The administrative distance (AD) is a measure of the trustworthiness of a routing protocol. The lower the AD, the more preferred the protocol is when the router learns about multiple routes to the same destination. For RIP (Routing Information Protocol), the default AD is 120, which is relatively high compared to other routing protocols like OSPF (which has an AD of 110) and EIGRP (which has an AD of 90). This means that RIP routes are less preferred by default than those learned via OSPF or EIGRP.
Option A, 90, is the AD for EIGRP.
Option B, 110, is the AD for OSPF.
Option D, 150, is not a typical default for any standard routing protocol.
RIP is one of the oldest routing protocols, and its AD reflects its less efficient, distance-vector nature compared to modern protocols like OSPF and EIGRP.
Question 36. Which of the following is the primary purpose of ACLs (Access Control Lists) in networking?
A) To control the flow of data within a specific VLAN.
B) To define routing policies in a network.
C) To filter network traffic based on IP addresses, protocols, or ports.
D) To prioritize traffic based on Quality of Service (QoS).
Answer: C)
Explanation:
An Access Control List (ACL) is a security feature used in networking to control which devices or users can communicate with each other across a network. ACLs are used on routers and firewalls to filter traffic and prevent unauthorized access based on a set of rules. These rules typically involve filtering based on IP addresses, protocols, and ports. ACLs act as a gatekeeper, allowing certain traffic to pass through while blocking or restricting other traffic based on predetermined criteria.
The primary function of ACLs is to filter network traffic. They are typically used for security purposes in network design and management. For instance, ACLs are applied to allow or deny certain types of traffic based on specific characteristics, such as the source IP address, destination IP address, protocol (TCP, UDP, ICMP, etc.), and port number. ACLs are often implemented in routers to control the flow of data between different network segments, or between the internal network and external networks (such as the internet).
For example, an ACL rule might be created to allow only HTTP traffic (on port 80) from a certain IP address to pass through the firewall, while blocking all other traffic. Similarly, ACLs can prevent certain devices or users from accessing sensitive network resources based on their IP addresses or by denying access to specific services.
Option A, controlling the flow of data within a specific VLAN, is not the function of ACLs. While ACLs can be applied to VLAN interfaces, they do not directly manage data flow within a VLAN. VLANs themselves handle the segmentation of broadcast domains in a network.
Option B, defining routing policies, is the role of routing protocols (such as OSPF, RIP, or BGP) or route maps—not ACLs. While ACLs may be used in some advanced routing configurations, their primary purpose is not to define the routing policy itself but to filter traffic based on access criteria.
Option D, prioritizing traffic based on QoS, is accomplished using Quality of Service (QoS) techniques such as traffic shaping and traffic policing, which ensure that higher-priority traffic (such as VoIP or video) gets preferential treatment. QoS settings are independent of ACLs, though both can be used together in some network configurations to improve overall performance and security.
ACLs are vital for ensuring security and traffic management in a network. Without them, devices and users might have unrestricted access to sensitive network segments, and it would be much harder to isolate specific traffic types for policy enforcement.
Question 37. What is the maximum number of VLANs that can be configured on a single Cisco switch, assuming the switch supports the full VLAN range?
A) 512
B) 1024
C) 4096
D) 8192
Answer: C)
Explanation:
The maximum number of VLANs that can be configured on a Cisco switch, when the switch supports the full VLAN range, is 4096. This is because VLANs are identified using a 16-bit identifier, known as the VLAN ID. The VLAN ID can be a number between 0 and 4095, which provides a total of 4096 potential VLANs. However, VLAN 0 and VLAN 4096 are reserved, meaning only 1 to 4095 are available for use in most network environments.
VLANs (Virtual Local Area Networks) are used to logically segment a network into smaller broadcast domains. By separating network traffic into different VLANs, network administrators can manage traffic more efficiently and ensure better performance and security by keeping unrelated or less secure devices separate from more critical parts of the network.
For example, an organization could set up VLANs for different departments (e.g., VLAN 10 for HR, VLAN 20 for Sales, VLAN 30 for IT) to ensure that traffic from one department does not interfere with or impact the performance of another department’s traffic. This logical segmentation allows for better traffic isolation and broadcast containment.
Option A, 512, is incorrect because the number of VLANs a switch can support is far greater than 512.
Option B, 1024, is also incorrect, as it underestimates the number of VLANs that a switch can support.
Option D, 8192, is incorrect because Cisco devices typically do not support more than 4096 VLANs. While other manufacturers may offer different configurations, Cisco switches are limited to a maximum of 4096 VLANs.
This large number of possible VLANs allows network administrators to design complex network topologies with a high degree of flexibility, enabling better management of different network segments and improving overall network efficiency.
Question 38. Which of the following IP address types is used for communication between devices on the same local network but is not routable over the internet?
A) Public IP
B) Private IP
C) Loopback IP
D) Multicast IP
Answer: B)
Explanation:
Private IP addresses are used for communication within a local network and are not routable over the Internet. These addresses are specifically reserved for use in internal networks, allowing organizations to conserve public IP addresses while still enabling communication between devices within the network. Private IPs cannot be directly accessed from the Internet, and if a device with a private IP needs to communicate with the outside world, it must use NAT (Network Address Translation) to convert its private IP into a public IP.
The range of private IP addresses as defined by RFC 1918 includes:
10.0.0.0 – 10.255.255.255 (Class A)
172.16.0.0 – 172.31.255.255 (Class B)
192.168.0.0 – 192.168.255.255 (Class C)
These ranges are commonly used for internal networking, whether it’s in a home, office, or enterprise environment. Private IP addresses help reduce the exhaustion of public IP addresses, especially in large networks, by allowing multiple devices to share a single public IP when accessing the Internet via NAT.
Option A, Public IP, refers to IP addresses that are globally routable over the Internet. Public IP addresses are assigned by the IANA (Internet Assigned Numbers Authority) and provide devices with unique identifiers that are accessible from anywhere on the web.
Option C, Loopback IP, refers to the 127.0.0.1 address, which is used to refer to the local machine itself. It allows a device to communicate with itself for testing purposes.
Option D, Multicast IP, is a class of IP addresses used for multicast communication, which allows data to be sent to multiple devices at once, but it is not used for general communication between devices within the same local network.
Using private IP addresses internally helps conserve public IP space and enhances network security by hiding the internal network structure from the external world.
Question 39. What is the purpose of VLAN trunking in a network?
A) To allow multiple VLANs to share a single physical link between switches.
B) To create virtual private networks (VPNs) over a public network.
C) To enforce strict access control between VLANs.
D) To allocate IP addresses dynamically to devices in different VLANs.
Answer: A)
Explanation:
VLAN trunking is a method used to allow multiple VLANs to share a single physical link between two network devices, such as switches. In this scenario, a trunk port is configured on both switches to allow the transmission of traffic for multiple VLANs over the same physical link. This reduces the number of required physical connections between switches, as a single trunk link can carry traffic for multiple VLANs simultaneously.
In Ethernet networking, the IEEE 802.1Q standard is used for VLAN tagging. It adds a tag to each Ethernet frame to specify which VLAN the frame belongs to. This tag enables the receiving device to correctly identify and process the frame, ensuring that traffic is directed to the appropriate VLAN. VLAN trunking is essential in large networks with multiple switches, as it allows VLANs to span across different switches while maintaining network segmentation and security.
Option B, creating VPNs, is the role of VPN technologies like IPsec or SSL, not VLAN trunking.
Option C, enforcing access control, is done using ACLs (Access Control Lists) or Layer 3 routing, not VLAN trunking.
Option D, dynamically allocating IP addresses, is the role of DHCP (Dynamic Host Configuration Protocol), not VLAN trunking.
VLAN trunking provides a cost-effective way to expand VLANs across a network, reducing the need for extensive physical cabling. It is critical for network scalability, enabling the use of many VLANs across multiple switches while keeping network traffic organized and efficient.
Question 40. What does Spanning Tree Protocol (STP) prevent in Ethernet networks?
A) Network congestion due to high traffic loads.
B) Switching loops that can cause broadcast storms.
C) Unauthorized access to network resources.
D) IP address conflicts between devices.
Answer: B)
Explanation:
Spanning Tree Protocol (STP) is a network protocol used to prevent switching loops in Ethernet networks. A switching loop occurs when there are multiple active paths between two or more network switches. If there is a loop in the network, broadcast frames sent by switches can circulate endlessly, consuming bandwidth and leading to a broadcast storm. This can bring the entire network to a standstill, as switches will continue forwarding broadcast frames without ever reaching their destination.
STP works by dynamically detecting and disabling redundant paths in the network. By doing so, it ensures that only one active path exists between switches, which eliminates the possibility of loops. In case of a failure of the active path, STP can quickly reconfigure the network by enabling one of the previously blocked redundant paths to maintain connectivity.
Option A, network congestion, is not directly related to STP. While STP helps avoid broadcast storms, it does not manage traffic loads or congestion.
Option C, preventing unauthorized access, is the role of network security protocols such as ACLs or 802.1X authentication.
Option D, preventing IP address conflicts, is the role of DHCP (Dynamic Host Configuration Protocol), not STP.
STP is critical in redundant network topologies where multiple paths exist, ensuring network stability and preventing potential data loss due to network loops.
