200-301 Cisco Certified Network Associate (CCNA) Exam Dumps and Practice Test Questions Set 2 Q21-40

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Question 21: 

A network engineer is configuring EIGRP on a router. The command network 192.168.10.0 0.0.0.255 is used. What does the 0.0.0.255 represent?

A) The network mask
B) The wildcard mask
C) The subnet ID
D) The default route

Answer: B

Explanation: 

In EIGRP, the wildcard mask specifies which bits of the IP address to match for the network statement. A 0 bit means the corresponding bit must match exactly, and a 1 bit means it can vary.

The command network 192.168.10.0 0.0.0.255 used in an EIGRP configuration tells the router which interfaces should participate in the routing process. The second value, 0.0.0.255, is known as a wildcard mask, which works almost like the inverse of a subnet mask. Each zero in the wildcard mask indicates that the corresponding bit in the IP address must match exactly, while each one allows variation. In this case, 0.0.0.255 means the first three octets must match 192.168.10, and the last octet can be any value from 0 to 255. This allows EIGRP to include all interfaces within that range. That’s why the correct answer is B)

Option A, the network mask, refers to the traditional subnet mask used for determining the network and host portions of an IP address. A subnet mask highlights the fixed and variable parts of an address by using ones for network bits and zeros for host bits. While wildcard masks appear related because they resemble inverse subnet masks, the two serve different purposes. The wildcard mask is specifically for protocol configuration like EIGRP or access lists, not for subnetting.Option C, the subnet ID, represents the actual network address of a subnet, such as 192.168.10.0. Although the network statement in the EIGRP configuration uses a subnet ID, the wildcard mask that follows it is not the subnet ID and does not identify a specific subnet; instead, it tells the router how broad the match should be.

Option D, the default route, is the route a router uses when no other specific route is available. A default route is normally written as 0.0.0.0/0 or configured with a command such as ip route 0.0.0.0 0.0.0.0 next-hop. It has no direct connection to the wildcard mask in the EIGRP network commanD)So, the value 0.0.0.255 is the wildcard mask that defines the range of addresses EIGRP should include.

Question 22: 

Which of the following describes a characteristic of a Layer 3 switch?

A) Operates only at Layer 2
B) Performs routing between VLANs internally
C) Cannot segment broadcast domains
D) Only forwards frames based on MAC addresses

Answer: B

Explanation: 

Layer 3 switches combine the high-speed switching of Layer 2 with routing capabilities, allowing them to route between VLANs without sending traffic to an external router.

A Layer 3 switch is basically the networking world’s multitasker. It blends the speedy frame-switching behavior of a traditional Layer 2 switch with the ability to perform routing decisions normally handled by a router. Because of this hybrid nature, the correct answer is B: it performs routing between VLANs internally. Instead of relying on an external router for inter-VLAN communication, it handles those routing tasks right inside the switch hardware. This cuts down on latency and keeps traffic flowing smoothly within a larger, segmented network.

Option A says it operates only at Layer 2. That would be true for a standard switch, but once routing capability enters the picture, the device definitely steps into Layer 3 territory. A Layer 3 switch can still do everything a Layer 2 switch does, like learning MAC addresses and forwarding frames, but it doesn’t stop there. It’s built to understand IP addressing and make forwarding decisions based on network-layer information.

Option C claims it cannot segment broadcast domains. In reality, this is exactly something a Layer 3 switch can do. When you create VLANs, you’re dividing the network into separate broadcast domains, and the switch handles that segmentation effortlessly. Each VLAN is isolated, and Layer 3 routing allows traffic to be passed between them only when needeD)

Option D says it only forwards frames based on MAC addresses. That’s describing a pure Layer 2 switch. A Layer 3 switch absolutely does use MAC-based forwarding within individual VLANs, but it also routes packets using IP addresses when traffic needs to cross boundaries. So it’s not restricted to one methoD)Overall, the defining trait is its ability to route internally between VLANs, making option B the spot-on choice.

Question 23: 

A network administrator wants to limit the number of DHCP addresses a switch can assign. Which feature should be configured?

A) DHCP snooping
B) DHCP pool
C) DHCP binding
D) DHCP relay

Answer: A

Explanation: 

DHCP snooping allows a switch to enforce policies for DHCP, such as limiting the number of leases per interface, protecting against rogue DHCP servers, and logging DHCP assignments.

When a network administrator wants to keep tight control over how many DHCP addresses a switch can hand out on a per-port basis, the tool that gets the job done is DHCP snooping, which makes option A the right call. DHCP snooping basically acts like a hall monitor for DHCP traffiC) It lets the switch decide which ports are allowed to send out DHCP offers and how many leases a device on a given interface is allowed to receive. This keeps rogue DHCP servers from poisoning the network and prevents a single device from grabbing a bunch of IPs it shouldn’t have.

Option B, DHCP pool, sounds like it might relate to limiting addresses, since it’s the place where you define the actual range of IPs a DHCP server can hand out. But a pool doesn’t let you enforce limits per interface or apply security policies. It just sets the available range; it doesn’t control how many leases a port can consume or filter suspicious behavior.Option C, DHCP binding, typically refers to a static mapping between a MAC address and an IP address. This is helpful when you want a device to always get the same address, but it doesn’t actually enforce how many IPs a device can acquire. It’s more about predictability than restriction.

Option D, DHCP relay, is all about forwarding DHCP requests across networks when the server isn’t on the same subnet. A relay agent doesn’t control address usage or guard the network from rogue servers. It just passes things along so the right server can responD)So the feature that steps in to limit address assignments, add oversight, and keep the DHCP process clean is definitely DHCP snooping. It gives the switch the authority to monitor, restrict, and log DHCP behavior right at the access layer.

Question 24: 

Which IPv6 address type is equivalent to IPv4 broadcast?

A) Unicast
B) Multicast
C) Anycast
D) IPv6 does not have a broadcast address

Answer: D

Explanation: 

IPv6 replaces broadcast with multicast and anycast. For example, all-nodes multicast (FF02::1) is used instead of broadcast to communicate with all nodes on a link.

IPv6 takes a different approach to network-wide communication compared to IPv4. Instead of relying on broadcast traffic, which sends a message to every device whether it wants it or not, IPv6 removes broadcast entirely. That makes option D the correct choice. IPv6 uses more efficient address types, such as multicast and anycast, to deliver traffic only to devices that actually need to receive it. For example, an all-nodes multicast address like FF02::1 can reach every device on a local link, but it still operates in a controlled way rather than flooding the network like IPv4 broadcast.

Option A, unicast, refers to communication between one device and another single specific device. This is a direct one-to-one form of transmission, both in IPv4 and IPv6. Since unicast is only intended for a single destination, it obviously cannot act as a replacement for broadcast behavior.

Option B, multicast, is much closer in spirit to what broadcast used to accomplish. Multicast targets a group of interested receivers instead of every device on the network. IPv6 leans heavily on multicast for functions like neighbor discovery and router advertisements. Even though multicast can reach multiple hosts at once, it isn’t the same thing as broadcast because only devices subscribed to a particular multicast group respond to the traffiC)

Option C, anycast, introduces a one-to-nearest model. Multiple devices share the same address, but only the nearest one (based on routing metrics) responds. This is useful for distributing services across multiple nodes but has nothing to do with a broadcast-style message that must reach all nodes.So the real answer is that IPv6 simply doesn’t use broadcast at all. Instead, it replaces that older mechanism with more refined and efficient communication methods such as multicast and anycast.

Question 25: 

What is the function of the show ip ospf neighbor command on a Cisco router?

A) Displays all OSPF routes
B) Shows OSPF interface configurations
C) Displays the current OSPF neighbors and their state
D) Shows OSPF process IDs only

Answer: C

Explanation: 

The command provides information about OSPF neighbors, including their IP addresses, router IDs, state (e.g., FULL), and adjacency details, helping troubleshoot OSPF issues.

The show ip ospf neighbor command is one of the go-to tools when you’re trying to get a handle on how OSPF is behaving on a Cisco router. Its purpose is to display details about the router’s OSPF neighbors and the state of the adjacencies, which lines up with option C) When you run the command, you see information like each neighbor’s router ID, the interface used to form the adjacency, the priority value, and the current state, such as FULL, 2-WAY, or EXSTART. This is essential for figuring out whether OSPF peering is forming correctly or if something is stuck in an unexpected state.

Option A, which says it shows all OSPF routes, actually describes what you’d expect from show ip route ospf. That command displays routes learned specifically through OSPF and the metrics associated with them. It doesn’t give you any real insight into neighbor relationships or adjacency formation.

Option B, showing OSPF interface configurations, refers more closely to the show ip ospf interface commanD) That one reveals settings like the network type, cost, timers, and DR/BDR election information for each interface running OSPF. While this info helps diagnose why a neighbor might not be forming, it’s not the same as listing actual neighbors.

Option D says it shows OSPF process IDs only. Process IDs identify separate OSPF instances running on a router, but the command for viewing them is typically show ip ospf or show running-config with OSPF sections. The neighbor-specific command doesn’t focus on process numbers alone.

So the purpose of show ip ospf neighbor is to give a clear picture of which neighbors exist, how far each adjacency has formed, and whether the OSPF relationship is healthy. This makes it a key troubleshooting command whenever OSPF seems grumpy or uncooperative.

Question 26: 

A company is designing a WAN connection with MPLS. What is the main advantage of using MPLS?

A) Provides encryption for all traffic
B) Reduces the number of required VLANs
C) Allows faster and more flexible path selection based on labels
D) Eliminates the need for IP addresses

Answer: C

Explanation: 

MPLS uses labels to forward packets along pre-determined paths, providing faster switching and the ability to prioritize traffic, unlike traditional IP routing.

MPLS is often chosen for WAN designs because it offers the ability to move traffic through the network using labels instead of relying solely on traditional IP lookups. This makes option C the correct answer. With MPLS, routers (often called label switch routers) make forwarding decisions based on short labels assigned to packets. These labels allow traffic to follow predetermined or optimized paths, enabling faster switching and more flexible route selection. MPLS also supports traffic engineering, letting network administrators prioritize certain applications or steer traffic through preferred routes without changing IP addressing.

Option A states that MPLS provides encryption for all traffic, but MPLS does not inherently encrypt datA) Although MPLS networks are generally private and considered secure from a service provider standpoint, encryption is not built in. If encryption is required, additional technologies such as IPsec tunnels must be layered on top of the MPLS connection.

Option B mentions reducing the number of required VLANs, which isn’t a function of MPLS. VLAN management occurs within a LAN environment, while MPLS is designed for wide-area traffic handling across service provider networks. MPLS does not change how VLANs are assigned or reduce their use; it simply carries traffic efficiently over the provider’s backbone.

Option D suggests MPLS eliminates the need for IP addresses. This is not accurate because MPLS still uses IP at the edge to classify traffic before labels are applieD) Devices and interfaces still require IP addressing, and routing protocols often work alongside MPLS to distribute reachability information.

The key advantage remains the label-based forwarding that speeds up packet handling and supports rich traffic engineering features, making MPLS a powerful option for modern WAN designs.

Question 27: 

Which command is used to prevent a router from advertising a specific route in OSPF?

A) no advertise route
B) distribute-list
C) passive-interface
D) route-filter

Answer: B

Explanation: 

A distribute-list in OSPF filters routes based on an access control list or prefix list, preventing specific routes from being advertised or installed in the routing table.

When you want to stop a router from advertising certain routes in an OSPF environment, the tool that gets the job done is a distribute-list, which makes option B correct. A distribute-list lets you apply filtering logic using an access list or prefix list. With it, you can tell OSPF exactly which routes should be blocked from being sent out or learneD) This is handy when you want tighter control of route propagation, prevent route leaks, or keep parts of the network isolated from unnecessary prefixes.

Option A, no advertise route, looks tempting because of the wording, but there is no such command in OSPF. OSPF doesn’t use a “no advertise” keyword for individual routes the way some other routing features might. Instead, OSPF relies on route filtering tools like distribute-lists or area-based filtering methods.

Option C, passive-interface, is definitely an important OSPF command, but it doesn’t stop a router from advertising specific routes. What it actually does is prevent OSPF from forming adjacencies on a particular interface. The router will still advertise routes, but it will not send OSPF hello packets out that interface. It’s mostly used for security or to keep unnecessary neighbor relationships from forming.

Option D, route-filter, isn’t an OSPF commanD) Some platforms or routing protocols use similar terminology, but Cisco OSPF relies on distribute-lists, prefix lists, and area-based mechanisms like stub or NSSA configurations for filtering. There is no built-in route-filter command that directly blocks OSPF advertisements.So the practical and correct tool for preventing a specific route from being advertised in OSPF is the distribute-list. It gives you a targeted, flexible way to shape routing behavior and keep the OSPF domain clean and predictable.

Question 28: 

Which type of access list is used to filter traffic based on source and destination IP addresses, protocols, and ports?

A) Standard ACL
B) Extended ACL
C) Named ACL
D) Reflexive ACL

Answer: B

Explanation: 

Extended ACLs can filter traffic based on multiple criteria, including source/destination IP addresses, Layer 4 protocols (TCP/UDP), and port numbers. Standard ACLs only filter based on source IP.

Extended ACLs are designed to give you fine-grained control over traffic by letting you filter based on several attributes at once. That makes option B the correct answer. With an extended ACL, you can match source and destination IP addresses, decide whether to act on specific Layer 4 protocols such as TCP, UDP, or ICMP, and even target particular ports like HTTP, DNS, or SSH. This flexibility lets administrators build very specific security rules and traffic controls, which is why extended ACLs are widely used in both enterprise networks and perimeter firewalls.

Option A, a standard ACL, works very differently. Standard ACLs only consider the source IP address when making decisions. They don’t look at what type of traffic it is or where it’s headeD) Because of this, standard ACLs are typically placed close to the destination so you don’t accidentally block more traffic than intendeD) They’re simple and fast but nowhere near as precise as extended ACLs.

Option C, named ACLs, often causes some confusion because both standard and extended ACLs can be named instead of numbereD) A named ACL is just an ACL identified with a name instead of a number; it does not change what the ACL can filter. You can choose whether the named ACL is standard or extended, so naming is really just an organizational convenience.

Option D, reflexive ACLs, adds a dynamic twist. These ACLs temporarily allow return traffic for outbound sessions by creating session entries on the fly, kind of like a lightweight firewall behavior. They don’t define filtering by protocol and port in the basic sense; instead, they rely on extended ACLs to build their rules. Reflexive ACLs are helpful for securing outbound sessions but they aren’t the primary tool for general filtering.So the ACL type that filters based on source, destination, protocol, and port is the extended ACL.

Question 29: 

A network administrator wants to verify the default gateway configuration on a host. Which command should be used on a Windows system?

A) ping
B) ipconfig
C) traceroute
D) nslookup

Answer: B

Explanation: 

The ipconfig command displays the host’s IP address, subnet mask, and default gateway. On Linux, the ip route or route -n command can be used for the same purpose.

When a network administrator needs to check the default gateway on a Windows machine, the command that provides this information directly is ipconfig, which makes option B the correct choice. Running ipconfig shows the host’s IPv4 and IPv6 addresses, subnet mask, and most importantly the default gateway. This information is essential for confirming whether the device knows where to send traffic destined for other networks. If the default gateway is missing or incorrect, the host won’t be able to reach anything outside its local subnet.

Option A, ping, is a diagnostic tool used to test connectivity. While you can ping the default gateway to verify it is reachable, ping doesn’t actually tell you what the default gateway is. You already need to know the gateway address before using ping, so it doesn’t help with discovering the configuration.

Option C, traceroute, performs path tracing to a destination by showing each hop along the route. On Windows, the command is actually tracert rather than traceroute. Even when used, it doesn’t reveal the default gateway setting directly. At best, the first hop in the trace is often the default gateway, but that only works when the route is functioning properly. It’s not meant for reading configuration details.

Option D, nslookup, deals exclusively with DNS. It helps resolve domain names to IP addresses and can query specific DNS servers. Since it’s focused on name resolution, it provides no information about local network configuration or gateway settings.

The command that cleanly displays the default gateway on a Windows system is ipconfig. It presents all the core network settings in one place, making it the simplest and most reliable choice when verifying basic TCP/IP configuration.

Question 30: 

A switch port is configured with switchport port-security. Which of the following actions occurs when a violation is detected?

A) The port continues to forward traffic
B) The port shuts down or restricts traffic depending on the violation mode
C) The switch sends an SNMP trap but allows all traffic
D) The switch ignores the violation

Answer: B

Explanation: 

Port security allows limiting the number of MAC addresses on a port. Violation modes include protect (drops violating traffic), restrict (drops traffic and increments a counter), and shutdown (puts the port in error-disabled state).

When a switch port is configured with port-security and a violation occurs, the response depends entirely on the violation mode. Because of that, option B is correct: the port either shuts down or restricts traffic depending on how the violation action is set. Port-security is designed to control which MAC addresses are allowed on an interface, protecting the network from unauthorized devices or MAC spoofing. The available modes include protect, restrict, and shutdown. Protect simply drops offending frames silently. Restrict also drops the frames but keeps a counter of violations and can generate alerts. Shutdown is the default and places the port into an error-disabled state, which stops all traffic and requires manual or automatic recovery.

Option A says the port continues to forward traffic, which is the opposite of how port-security works. Once a violation occurs, the switch must take some form of action to enforce the rule. Allowing all traffic would defeat the entire purpose of limiting MAC addresses.

Option C states that the switch sends an SNMP trap but permits all traffiC) While the restrict mode can send notifications, it does not allow traffic from the violating MAC address. Any violation still results in dropped frames or a shutdown of the port depending on the configured mode.

Option D, which claims the switch ignores the violation, doesn’t line up with how port-security behaves. Port-security is specifically designed to react to unauthorized MAC activity. Ignoring violations would leave the port vulnerable to attacks like MAC flooding or unauthorized device connections.

So when a violation happens, port-security doesn’t just let it slide; it enforces protection according to the selected mode. That might mean quietly dropping frames, logging the event, or completely shutting the interface down, depending on the configuration.

Question 31: 

Which command is used to enable RIP on a Cisco router?

A) router rip
B) ip route rip
C) router eigrp 1
D) router ospf 1

Answer: A

Explanation: 

The router rip command enables RIP routing protocol. Additional network statements specify which interfaces participate in RIP.

The command used to enable RIP on a Cisco router is router rip. This command is entered in global configuration mode and serves as the initial step to activate the Routing Information Protocol on the device. Once this command is issued, the router transitions into RIP configuration mode, allowing further settings to be applied, such as specifying which networks will participate in RIP.

RIP, or Routing Information Protocol, is a distance-vector routing protocol that uses hop count as its metric to determine the best path to a destination network. The maximum number of hops allowed in RIP is 15, meaning any network more than 15 hops away is considered unreachable. The router rip command enables the router to advertise its directly connected networks to other RIP-enabled routers and to receive routing updates from them, facilitating dynamic routing.

After enabling RIP with router rip, network statements are used to indicate which interfaces should send and receive RIP updates. For example, the network 192.168.1.0 command would include all interfaces that fall within the 192.168.1.0 network range in RIP advertisements. These network statements are essential because only networks listed under RIP will participate in routing updates, while other networks will not be advertiseD)

The other options provided do not enable RIP. The command ip route rip is incorrect because IP routing commands are used for static routes, not for enabling a dynamic routing protocol. router eigrp 1 activates the Enhanced Interior Gateway Routing Protocol, which is entirely separate from RIP and uses a different metric based on bandwidth and delay. router ospf 1 enables the Open Shortest Path First protocol, a link-state protocol that uses cost as a metric rather than hop count, and it also requires different configuration commands.Overall, router rip is the correct command to activate RIP on a Cisco router, allowing the device to dynamically exchange routing information using hop count as the metric and to participate in a RIP-based network.

Question 32: 

In a LAN environment, which duplex mode combination can cause collisions?

A) Full duplex on both ends
B) Half duplex on both ends
C) Mismatched duplex (one half, one full)
D) Both full with flow control

Answer: C

Explanation: 

Duplex mismatch occurs when one end is set to half-duplex and the other to full-duplex. This can lead to late collisions and degraded network performance.

In a LAN environment, the combination of duplex settings on connected devices plays a critical role in determining network performance and collision behavior. The scenario that can cause collisions is a mismatched duplex configuration, where one end of the connection is set to half duplex and the other end is set to full duplex. In this situation, the full-duplex device can transmit data at any time without concern for collisions, while the half-duplex device follows the Carrier Sense Multiple Access with Collision Detection (CSMA/CD) protocol and expects to detect collisions before transmitting. This mismatch leads to late collisions, as the half-duplex device may sense the medium as idle while the full-duplex device is already transmitting. Consequently, network performance degrades, with packet loss and retransmissions increasing latency and reducing throughput.

If both ends are configured for full duplex, collisions do not occur because full-duplex mode allows simultaneous transmission and reception without relying on CSMA/CD) This is the optimal configuration for modern Ethernet networks, especially when using switches, as each link operates independently.

Similarly, if both ends are set to half duplex, collisions can occur, but they are normal and expected within the CSMA/CD framework. The network handles collisions through retransmission mechanisms, so while performance may not be as high as full duplex, collisions do not indicate a configuration problem.

The option of both ends being full duplex with flow control enabled does not cause collisions either. Flow control mechanisms, such as IEEE 802.3x, prevent buffer overflows by pausing transmissions when needed, ensuring smooth communication without introducing collisions.

Therefore, the specific issue arises only when there is a duplex mismatch. It is essential for network administrators to verify and align the duplex settings on both ends of a connection to avoid unexpected collisions and performance degradation. Properly matched duplex configurations ensure efficient use of bandwidth and maintain reliable communication across the network.

Question 33: 

Which of the following is a key difference between TCP and UDP?

A) TCP is faster than UDP
B) TCP provides error recovery and sequencing, UDP does not
C) UDP guarantees delivery of packets
D) TCP does not use ports

Answer: B

Explanation: 

TCP is connection-oriented, provides sequencing, acknowledgments, and error recovery. UDP is connectionless and does not guarantee delivery.

A key difference between TCP and UDP lies in how each protocol handles data transmission and reliability. TCP, or Transmission Control Protocol, is a connection-oriented protocol, meaning that it establishes a session between the sender and receiver before any data is transmitteD) This connection-oriented approach allows TCP to provide several important features, including sequencing of packets, acknowledgment of received data, and error recovery. Sequencing ensures that packets arrive in the correct order, even if they take different paths through the network. Acknowledgments allow the sender to know which packets have been successfully received, and error recovery mechanisms ensure that lost or corrupted packets are retransmitteD) These features make TCP reliable for applications where accurate and complete delivery of data is critical, such as web browsing, email, and file transfers.

In contrast, UDP, or User Datagram Protocol, is connectionless. It sends packets, called datagrams, without establishing a session or verifying receipt. UDP does not provide sequencing, acknowledgments, or error recovery, meaning that packets may arrive out of order, be duplicated, or be lost entirely without notice. This lack of overhead makes UDP faster than TCP in terms of raw transmission speed, which is why it is commonly used for real-time applications like video streaming, online gaming, and voice over IP, where speed and low latency are more important than absolute reliability.

The other options in the question are incorrect. TCP is generally slower than UDP due to the additional overhead of connection management, sequencing, and error recovery, so it is inaccurate to say TCP is faster. UDP does not guarantee delivery of packets, so that option is incorrect. Finally, TCP does use ports to direct traffic to specific applications, making the statement that TCP does not use ports false.

In summary, the most significant distinction is that TCP provides error recovery, sequencing, and reliable delivery, whereas UDP operates without these guarantees, focusing on speed and low-latency communication. This difference determines which protocol is appropriate for different network applications.

Question 34: 

A network engineer notices high CPU utilization on a router due to routing updates. Which protocol might be the cause in a large network?

A) OSPF
B) EIGRP
C) RIP
D) BGP

Answer: C

Explanation: 

RIP sends periodic full updates every 30 seconds, which can cause high CPU utilization on large networks. OSPF and EIGRP send incremental updates, reducing loaD)

In a large network, high CPU utilization on a router caused by frequent routing updates is often associated with the Routing Information Protocol, or RIP. RIP is a distance-vector routing protocol that uses hop count as its metric, with a maximum limit of 15 hops. One of RIP’s defining characteristics is that it sends complete routing table updates to all neighboring routers at fixed intervals, typically every 30 seconds. In a small network, this behavior has minimal impact, but in larger networks with many routes and routers, these periodic full-table updates can generate significant processing overhead, leading to high CPU utilization. Each update requires the router to process incoming routes, compare them to the current routing table, and determine if changes need to be applied, which consumes processing resources.

Other routing protocols handle updates more efficiently. Open Shortest Path First (OSPF) is a link-state protocol that sends updates only when there is a change in the network topology. Instead of broadcasting the entire routing table, OSPF uses Link-State Advertisements (LSAs) to communicate changes, significantly reducing the amount of processing and network traffic compared to RIP. Similarly, Enhanced Interior Gateway Routing Protocol (EIGRP) is an advanced distance-vector protocol that uses incremental updates rather than periodic full-table broadcasts. EIGRP sends updates only when a route changes and only the affected portions of the routing table, which lowers CPU load and conserves bandwidth. Border Gateway Protocol (BGP), used primarily for interdomain routing, also updates routes incrementally and is designed to scale to very large networks, making it unlikely to cause high CPU utilization solely due to regular updates.

Therefore, in a large network, RIP’s reliance on periodic full-table updates is the primary factor that can lead to high CPU utilization on a router. Network engineers often replace RIP with more efficient protocols like OSPF or EIGRP in larger environments to reduce processing demands and improve overall network performance.

Question 35: 

Which IP address is automatically assigned when a host cannot contact a DHCP server?

A) APIPA (169.254.x.x)
B) Loopback (127.x.x.x)
C) Default gateway
D) Broadcast address

Answer: A

Explanation: 

APIPA (Automatic Private IP Addressing) assigns an address in the 169.254.0.0/16 range when DHCP fails, allowing limited local connectivity.When a host attempts to obtain an IP address from a DHCP server but is unable to contact one, it can automatically assign itself an address using Automatic Private IP Addressing, or APIPA) APIPA assigns an IP address from the 169.254.0.0/16 range, which is reserved specifically for this purpose. This process allows the host to maintain limited local network connectivity, enabling communication with other devices on the same subnet that are also using APIPA addresses. APIPA is commonly used in Windows environments but is supported in other operating systems as well.

The other options listed do not serve the same function. The loopback address range, 127.0.0.0/8, is used for a host to communicate with itself for testing and diagnostics; it does not facilitate communication with other hosts on a network. The default gateway is the IP address of a router that forwards traffic from the local network to other networks, but it is not automatically assigned to a host when DHCP fails. A broadcast address is used to send data to all devices on a subnet, but it also is not automatically assigned to a host as an IP address.

APIPA is particularly useful for small networks or in situations where a DHCP server may be temporarily unavailable. While it does not provide connectivity to external networks, it allows hosts to continue communicating locally without manual IP configuration. Once the DHCP server becomes available, the host can obtain a proper IP address and subnet information, replacing the APIPA address automatically.

Question 36: 

In STP, which port is selected as the root port?

A) The port with the highest MAC address
B) The port with the lowest cost to the root bridge
C) Any port on the root bridge
D) All designated ports on the switch\

Answer: B

Explanation: 

The root port is the port on a switch with the lowest path cost to the root bridge. It is the primary forwarding path toward the root bridge.In Spanning Tree Protocol (STP), the root port plays a crucial role in preventing loops while ensuring efficient network traffic forwarding. The root port is the single port on a non-root switch that provides the best path toward the root bridge. Specifically, it is the port with the lowest cumulative path cost to reach the root bridge. Path cost is calculated based on the bandwidth of each link in the path; higher-speed links have lower costs, making them preferred for forwarding traffiC) By selecting the port with the lowest cost, STP ensures that traffic flows along the most efficient route to the root bridge, reducing delays and avoiding network loops.

The other options listed in the question are not correct. Selecting the port with the highest MAC address is unrelated to root port selection because STP decisions are based on path cost, bridge ID, and port ID, not MAC address values. While all ports on the root bridge play a special role, they are designated ports rather than root ports; the root bridge does not need a root port because it is the reference point for the network. Similarly, all designated ports on a switch are responsible for forwarding traffic toward downstream switches, but designated ports are selected based on which switch has the lowest path cost to the root for a given network segment, not for connecting back to the root bridge.

 

By identifying the port with the lowest cost to the root bridge, STP ensures a loop-free topology. The root port becomes the primary forwarding interface for frames traveling toward the root, while other ports may be placed in a blocking or alternate state if necessary to prevent loops. This mechanism allows STP to maintain network redundancy while ensuring that traffic always follows the most efficient path.

Question 37: 

Which IPv6 address is used for multicast to all nodes on a local link?

A) FF02::1
B) FF02::2
C) FE80::1
D) FF00::1

Answer: A

Explanation: 

FF02::1 is the all-nodes multicast address used to reach all IPv6 nodes on a link. FF02::2 is all-routers, and FE80::/10 is link-local unicast.

In IPv6, multicast addresses are used to send a single packet to multiple devices within a specific scope, eliminating the need to broadcast to all hosts as in IPv4. The address FF02::1 is designated as the all-nodes multicast address for the link-local scope. This means that any packet sent to FF02::1 will be received by all IPv6-enabled devices on the same local link. It allows efficient communication with all nodes without relying on broadcast, which no longer exists in IPv6. Network protocols and services often use this address for tasks like neighbor discovery, network announcements, or sending updates to all nodes on a subnet.

The other options represent different types of addresses in IPv6. FF02::2 is the all-routers multicast address, which targets only routers on the local link. This address is used for communication specifically with routers, for example, when a host needs to discover the presence of routers or send routing protocol messages. FE80::/10 represents the link-local unicast address range, which is assigned to every IPv6 interface and is used for communication between devices on the same link but not for multicast. Each host has a unique link-local address, allowing point-to-point communication within the local segment. FF00::1 is not a valid standard multicast address; FF00::/8 is the general multicast prefix, and the lower-order bits determine the specific group and scope, so FF00::1 does not represent all nodes or a commonly used multicast group.

Using FF02::1 ensures that messages intended for all nodes on a local link are delivered efficiently, without unnecessary routing or broadcast traffiC) It is a key component of IPv6’s design to replace broadcast with more precise multicast communication, improving scalability and reducing unnecessary network loaD) The address is essential for many IPv6 network operations and is widely used in protocols that rely on communication with all local nodes.

Question 38: 

A router receives an OSPF update from a neighbor. Which of the following is used to uniquely identify the neighbor?

A) IP address
B) Router ID
C) MAC address
D) Subnet mask

Answer: B

Explanation: 

OSPF uses the Router ID (a 32-bit number) to uniquely identify each router in the OSPF domain and ensure correct routing database updates.

In OSPF, identifying neighbors accurately is crucial for building and maintaining a consistent routing topology. When a router receives an OSPF update from a neighbor, it uses the neighbor’s Router ID to uniquely identify the sending router. The Router ID is a 32-bit number, typically represented in IPv4 address format, and is unique within the OSPF domain. It ensures that OSPF routers can differentiate between neighbors even if multiple routers exist on the same subnet or share overlapping IP addresses. By using the Router ID, OSPF avoids confusion in the link-state database and ensures that routing information is correctly associated with the right router.

The other options in the question are not suitable for uniquely identifying OSPF neighbors. While an IP address is associated with a router’s interface and is used for neighbor communication, it is not guaranteed to be unique across the entire OSPF domain. Multiple routers may share IP subnets or have addresses that change dynamically, so relying solely on IP addresses could lead to misidentification. MAC addresses operate at Layer 2 and are used for local network communication, but OSPF is a Layer 3 protocol and does not depend on MAC addresses to track routing information. Subnet masks define the size of an IP network and help in routing decisions, but they do not uniquely identify individual routers in the OSPF domain.

The Router ID can be manually configured by the network administrator or automatically selected based on the highest IP address on the router’s active interfaces. Once selected, the Router ID remains constant for the OSPF process, even if interface IP addresses change, providing a stable identifier for the duration of the OSPF session. This stability is critical because OSPF uses link-state advertisements (LSAs) to update routing information, and these LSAs are tagged with the Router ID to indicate the source of each update.

Question 39: 

Which type of NAT translates a single public IP to multiple private IPs with different port numbers?

A) Static NAT
B) Dynamic NAT
C) PAT (Port Address Translation)
D) Overlapping NAT

Answer: C

Explanation: 

PAT allows multiple private IPs to share a single public IP using unique port numbers for each session, also known as NAT overload.

Question 40: 

A network administrator wants to verify which VLANs are active on a switch. Which command should be used?

A) show vlan brief
B) show ip route
C) show interfaces
D) show spanning-tree

Answer: A

Explanation: 

The show vlan brief command displays all VLANs configured on a switch, their status, and which ports are assigned to each VLAN.

To verify which VLANs are active on a switch, the command show vlan brief is the most appropriate. This command provides a concise overview of all VLANs configured on the switch, including their VLAN IDs, names, status (active or suspended), and the list of ports assigned to each VLAN. By using this command, a network administrator can quickly determine which VLANs are operational, which ones are administratively down, and which switch ports are participating in each VLAN. This information is critical for troubleshooting connectivity issues, planning network segmentation, and ensuring proper VLAN configuration across the switch.

The other options are not suitable for checking VLAN status. The command show ip route displays the routing table of a router or Layer 3 switch, including learned routes, connected networks, and static routes, but it does not provide information about VLANs or port assignments. The command show interfaces provides detailed statistics and status for physical and logical interfaces, including whether interfaces are up or down, error counts, and interface speed and duplex, but it does not summarize VLAN information across the switch. The show spanning-tree command displays Spanning Tree Protocol information, such as root bridge, port roles, and port states, which helps prevent loops in the network. While it can show which ports are forwarding or blocking in a particular VLAN, it does not provide a comprehensive list of all active VLANs or their associated ports.

Using show vlan brief gives a complete and organized view of the VLAN configuration. Each VLAN is listed with its VLAN ID and name, and the status column indicates whether the VLAN is active, suspended, or not in use. The ports assigned to each VLAN are also displayed, helping administrators verify that the intended devices are connected to the correct VLANs. This command is essential for VLAN management and ensures proper segmentation and organization of network traffic.

In summary, show vlan brief is the command that allows network administrators to view all configured VLANs, their current operational status, and associated ports, whereas the other commands focus on routing, interface statistics, or Spanning Tree information rather than VLAN overview.