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CNEpv practice questions

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Question 1Network Fundamentals, Architecture, and Topologies

Which OSI layer is responsible for logical addressing and path selection between networks?

  1. Network layer Correct answer.
  2. Transport layer
  3. Data link layer
  4. Session layer

Explanation

The network layer handles logical (IP) addressing and routing decisions that move packets between different networks. The data link layer deals with physical addressing on a single link, while transport and session layers handle end-to-end delivery and dialog control.

Question 2Network Fundamentals, Architecture, and Topologies

A workstation with IP address 192.168.10.77 and mask 255.255.255.192 needs to reach a host at 192.168.10.130. What does the workstation conclude?

  1. The destination is on the local subnet, so traffic is sent directly via ARP
  2. The destination requires a subnet mask change before sending
  3. The destination is a broadcast address and is dropped
  4. The destination is on a remote subnet, so traffic goes to the default gateway Correct answer.

Explanation

A /26 mask gives subnets of 64 addresses: 192.168.10.64-127 and 192.168.10.128-191. The source .77 falls in the first subnet and the destination .130 falls in the second, so the host is remote and frames must go to the gateway.

Question 3Network Fundamentals, Architecture, and Topologies

Which device primarily operates at Layer 2 and builds a table of MAC addresses mapped to switch ports?

  1. Hub
  2. Ethernet switch Correct answer.
  3. Firewall
  4. Router

Explanation

A Layer 2 switch learns source MAC addresses and associates them with the ports they arrive on, then forwards frames based on that table. Routers forward based on Layer 3 addresses, hubs repeat signals blindly, and firewalls filter traffic by policy.

Question 4Network Fundamentals, Architecture, and Topologies

A network engineer needs a topology in which every device has a dedicated point-to-point link to a central device. Which topology is described?

  1. Star Correct answer.
  2. Bus
  3. Full mesh
  4. Ring

Explanation

A star topology connects each endpoint to a central device such as a switch, giving dedicated links per device. Full mesh interconnects every node to every other node, bus shares one medium, and ring passes traffic node to node in a loop.

Question 5Network Fundamentals, Architecture, and Topologies

Which characteristic distinguishes TCP from UDP at the transport layer?

  1. TCP uses port numbers while UDP does not
  2. TCP provides connection-oriented, reliable delivery with acknowledgments Correct answer.
  3. TCP operates only on local subnets
  4. TCP is connectionless and best-effort

Explanation

TCP establishes a connection, sequences segments, and uses acknowledgments and retransmissions to provide reliable delivery. UDP is connectionless and best-effort but still uses port numbers for multiplexing.

Question 6Network Fundamentals, Architecture, and Topologies

An administrator sees a route marked as directly connected in the routing table. What does this indicate?

  1. The route is a static default route
  2. The route is associated with an interface that is up and configured with an IP address Correct answer.
  3. The route was learned from a dynamic routing protocol
  4. The route is a floating static backup

Explanation

Directly connected routes appear automatically when an interface is up and has an IP address and mask assigned. They are not learned from routing protocols or manually configured as static entries.

Question 7Network Fundamentals, Architecture, and Topologies

What is the primary purpose of ARP on an IPv4 network?

  1. To resolve a MAC address to an IP address for remote hosts
  2. To assign IP addresses dynamically to clients
  3. To translate private addresses to public addresses
  4. To resolve an IP address to a MAC address on the local segment Correct answer.

Explanation

ARP broadcasts a request asking which device owns a given IPv4 address and receives the corresponding MAC address in the reply. This mapping is needed to build the Layer 2 frame for local delivery.

Question 8Network Fundamentals, Architecture, and Topologies

Which statement best describes a VLAN?

  1. A physical cable segment shared by all devices
  2. A logical broadcast domain created on switches independent of physical location Correct answer.
  3. A routing protocol used between switches
  4. A security zone defined only on firewalls

Explanation

A VLAN groups switch ports into a logical broadcast domain, so devices can be separated regardless of physical cabling. Broadcasts stay within the VLAN, and inter-VLAN traffic must be routed.

Question 9Network Fundamentals, Architecture, and Topologies

A company has four /24 subnets and needs a single summarized route for them: 10.1.0.0/24, 10.1.1.0/24, 10.1.2.0/24, and 10.1.3.0/24. Which summary is correct?

  1. 10.1.0.0/21
  2. 10.1.0.0/23
  3. 10.1.0.0/24
  4. 10.1.0.0/22 Correct answer.

Explanation

The four /24 networks share the first 22 bits, since the third octet values 0-3 fit within the /22 range 10.1.0.0-10.1.3.255. A /22 mask of 255.255.252.0 covers exactly those four subnets without including extra space.

Question 10Network Fundamentals, Architecture, and Topologies

Which IPv6 address type is used for one-to-many delivery to all interested receivers?

  1. Unicast
  2. Anycast
  3. Multicast Correct answer.
  4. Broadcast

Explanation

IPv6 multicast delivers packets to all interfaces that have joined the group. IPv6 has no broadcast type; anycast delivers to the nearest member of a group, and unicast is one-to-one.

Question 11Network Fundamentals, Architecture, and Topologies

A host configured with the address 169.254.12.5/16 is most likely experiencing which condition?

  1. Failure to obtain a DHCP lease Correct answer.
  2. Successful DHCP lease from a server
  3. A loopback misconfiguration
  4. Static assignment from a public pool

Explanation

The 169.254.0.0/16 range is link-local (APIPA), which a host self-assigns when DHCP is unreachable. Seeing this address usually means the client could not contact a DHCP server.

Question 12Network Fundamentals, Architecture, and Topologies

What does the administrative distance of a route represent?

  1. The maximum transmission unit along the path
  2. The trustworthiness of the route source when multiple routes to the same prefix exist Correct answer.
  3. The bandwidth cost of the path
  4. The number of hops to the destination

Explanation

Administrative distance ranks route sources so a router can choose among competing routes to the same destination, with lower values preferred. It is separate from the metric, which measures path cost within a single protocol.

Question 13Network Fundamentals, Architecture, and Topologies

Which protocol uses a three-way handshake to establish a session before data transfer?

  1. UDP
  2. TCP Correct answer.
  3. ARP
  4. ICMP

Explanation

TCP opens a connection with SYN, SYN-ACK, and ACK before any data is exchanged. This handshake synchronizes sequence numbers and confirms both endpoints are ready.

Question 14Network Fundamentals, Architecture, and Topologies

A frame arrives at a switch for a destination MAC address that is not in the MAC address table. What does the switch typically do?

  1. Drops the frame
  2. Rewrites the destination MAC to the gateway
  3. Sends the frame back out the ingress port
  4. Floods the frame out all ports in the same VLAN except the ingress port Correct answer.

Explanation

When the destination MAC is unknown, the switch floods the frame within the VLAN so the destination can respond and be learned. Once the reply is seen, the MAC-to-port mapping is added to the table.

Question 15Network Fundamentals, Architecture, and Topologies

Which statement correctly describes the difference between a collision domain and a broadcast domain?

  1. Both terms describe the same set of devices on a VLAN
  2. A collision domain includes all devices sharing a segment where frames can collide, while a broadcast domain includes all devices that receive a broadcast Correct answer.
  3. A collision domain is bounded by routers, and a broadcast domain is bounded by switches
  4. A broadcast domain is limited to a single switch port

Explanation

A collision domain is the set of devices whose frames can collide on a shared medium, and switches separate these per port. A broadcast domain is the set of devices that receive a broadcast frame, which a VLAN or router boundary defines.

Question 16Network Fundamentals, Architecture, and Topologies

What role does the default gateway serve for an end host?

  1. It provides Layer 2 address learning
  2. It assigns the host its IP address
  3. It resolves domain names to IP addresses
  4. It forwards traffic destined for networks outside the host's local subnet Correct answer.

Explanation

The default gateway is the router interface a host sends to when the destination is not on its local subnet. The host compares the destination against its own mask and forwards off-subnet traffic to the gateway.

Question 17Network Fundamentals, Architecture, and Topologies

A network uses OSPF and has two equal-cost paths to the same destination. How does the router handle traffic by default?

  1. It load-balances traffic across both paths Correct answer.
  2. It drops traffic until one path fails
  3. It sends all traffic on the path with the higher cost
  4. It installs only one path and ignores the other

Explanation

When multiple paths have the same lowest metric, OSPF supports equal-cost multipath and the router installs both routes. Traffic is then shared across the paths, improving utilization and resilience.

Question 18Network Fundamentals, Architecture, and Topologies

Which address range is reserved for private use under RFC 1918?

  1. 172.16.0.0/12 Correct answer.
  2. 192.0.2.0/24
  3. 198.51.100.0/24
  4. 172.0.0.0/8

Explanation

RFC 1918 defines 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16 as private ranges. The 172.16.0.0/12 block spans 172.16.0.0 through 172.31.255.255.

Question 19Network Fundamentals, Architecture, and Topologies

What is the effect of configuring a port as an access port versus a trunk port on a switch?

  1. An access port carries a single VLAN, while a trunk port carries multiple VLANs using tagging Correct answer.
  2. An access port carries multiple VLANs, while a trunk port carries only one
  3. Both port types carry exactly one VLAN
  4. A trunk port disables VLAN tagging entirely

Explanation

An access port belongs to one VLAN and sends untagged frames to end devices. A trunk port carries traffic for multiple VLANs and uses 802.1Q tags to identify each frame's VLAN.

Question 20Network Fundamentals, Architecture, and Topologies

A network designer wants redundancy so that loss of a single link does not isolate any site. Which design principle is being applied?

  1. Scalability
  2. High availability through redundancy Correct answer.
  3. Quality of service
  4. Address summarization

Explanation

Redundant links and devices provide alternate paths so a single failure does not cause an outage, which is the goal of high availability. Scalability addresses growth, QoS addresses traffic treatment, and summarization reduces routing table size.

Question 21Network Fundamentals, Architecture, and Topologies

Which statement accurately describes the behavior of a router when it receives a packet whose destination network is not in its routing table and no default route exists?

  1. It drops the packet and may send an ICMP unreachable message Correct answer.
  2. It forwards the packet to the nearest switch
  3. It floods the packet out all interfaces
  4. It rewrites the destination address to a local host

Explanation

Without a matching route or default route, the router has no path and discards the packet. It typically returns an ICMP destination unreachable message to the source.

Question 22Network Fundamentals, Architecture, and Topologies

A host must send a packet to 2001:db8::5, which is on a remote subnet. What does the host do first?

  1. It performs neighbor discovery for its default gateway and sends the packet to the gateway's link-layer address Correct answer.
  2. It sends the packet directly to the destination MAC address
  3. It sends an ARP broadcast for the destination
  4. It drops the packet because IPv6 has no gateways

Explanation

For an off-link IPv6 destination, the host uses neighbor discovery to learn the gateway's link-layer address and forwards the packet to that gateway. IPv6 uses neighbor discovery rather than ARP broadcasts.

Question 23Network Fundamentals, Architecture, and Topologies

An engineer observes that a switch port connected to a workstation is receiving frames tagged with VLAN 20, but the port is configured as an access port in VLAN 10. What is the most likely result?

  1. The switch automatically converts the port to a trunk
  2. The tagged frames are dropped or mishandled because the access port does not expect tags Correct answer.
  3. The frames are routed to VLAN 20 by the switch
  4. The frames are forwarded normally into VLAN 10

Explanation

An access port expects untagged frames for its assigned VLAN, so receiving 802.1Q-tagged frames is a mismatch. The switch will typically drop or misclassify those frames rather than translate them.

Question 24Network Fundamentals, Architecture, and Topologies

Which statement best explains why a full mesh WAN topology is rarely chosen for large networks?

  1. It limits each node to a single connection
  2. It provides too little redundancy
  3. The number of links grows rapidly with each added node, raising cost and complexity Correct answer.
  4. It cannot support routing protocols

Explanation

In a full mesh, every node connects to every other node, so the link count grows roughly with the square of the node count. That gives excellent redundancy but high cost and management burden as the network scales.

Question 25Network Fundamentals, Architecture, and Topologies

A technician must choose between a routed (Layer 3) access layer and a traditional Layer 2 access layer with VLANs. Which consideration favors the routed access design?

  1. It requires all hosts to share one subnet
  2. It reduces dependence on large broadcast domains and spanning tree by routing at the access layer Correct answer.
  3. It removes the need for any default gateway
  4. It eliminates the need for IP addressing

Explanation

Routing at the access layer creates smaller Layer 3 domains, which limits broadcast scope and reduces reliance on spanning tree for loop prevention. Hosts still need addressing and gateways; the benefit is a more resilient, segmented design.

Question 26Network Fundamentals, Architecture, and Topologies

Which topology connects every device to a single central device, so that a failure of that central device disables the entire network?

  1. Star topology Correct answer.
  2. Bus topology
  3. Mesh topology
  4. Ring topology

Explanation

In a star topology, all end devices connect to a central device such as a switch or hub. If the central device fails, every attached device loses connectivity, which is the single point of failure described. Other topologies distribute connectivity differently and do not depend on one central node in the same way.

Question 27Network Fundamentals, Architecture, and Topologies

Which OSI layer is responsible for logical addressing and path selection between different networks?

  1. Network layer Correct answer.
  2. Transport layer
  3. Physical layer
  4. Data link layer

Explanation

The network layer, Layer 3, handles logical addressing such as IP addresses and determines the best path for packets across multiple networks. Routers operate primarily at this layer to forward traffic between subnets.

Question 28Network Fundamentals, Architecture, and Topologies

A network engineer is designing a new office network and wants to reduce the size of broadcast domains without adding routers. Which solution should be used?

  1. Connect all switches with a single uplink
  2. Assign all devices to the same VLAN
  3. Replace switches with hubs
  4. Implement VLANs on the switches Correct answer.

Explanation

VLANs logically segment a switched network into separate broadcast domains. Devices in different VLANs do not receive each other's broadcast traffic, even though they connect to the same physical switches, which reduces broadcast domain size without requiring routers.

Question 29Network Fundamentals, Architecture, and Topologies

Which statement accurately describes the difference between a routed access layer and a traditional Layer 2 access layer with VLANs?

  1. A routed access layer supports only wireless clients, while a Layer 2 access layer supports only wired clients.
  2. A routed access layer uses VLANs to segment broadcast domains, while a Layer 2 access layer uses routing protocols.
  3. A routed access layer places Layer 3 boundaries at the access switches, while a Layer 2 access layer extends VLANs to the distribution layer. Correct answer.
  4. A routed access layer requires Spanning Tree Protocol on all access switches, while a Layer 2 access layer does not.

Explanation

In a routed access layer design, each access switch performs Layer 3 routing, so broadcast domains terminate at the access switch and VLANs are not extended beyond it. In a traditional Layer 2 access layer, VLANs are trunked to distribution switches, which handle inter-VLAN routing.

Question 30Network Fundamentals, Architecture, and Topologies

A network designer is planning a WAN connecting five sites and wants to ensure that no single link failure isolates any site. Which topology should be selected?

  1. Point-to-point
  2. Hub-and-spoke
  3. Full mesh Correct answer.
  4. Partial mesh

Explanation

A full mesh connects every site directly to every other site, providing redundant paths so that the loss of any single link still leaves each site reachable through alternate routes. Hub-and-spoke and partial mesh designs can isolate a site if a critical link fails.

Question 31Routing Protocols and Switching Technologies

In a switched Ethernet LAN, what is the primary purpose of the Spanning Tree Protocol (STP)?

  1. To distribute IP subnets between VLANs
  2. To prevent Layer 2 forwarding loops by blocking redundant paths Correct answer.
  3. To authenticate hosts before they join the network
  4. To load-balance traffic across equal-cost routed links

Explanation

STP builds a loop-free logical topology by electing a root bridge and placing redundant ports into a blocking state. Without it, broadcast frames would circulate indefinitely in a redundant Layer 2 topology. It operates at Layer 2 and does not perform routing, load balancing, or authentication.

Question 32Routing Protocols and Switching Technologies

Which statement describes the default behavior of a Cisco switch port configured with the dynamic auto switchport mode when connected to a port in dynamic desirable mode?

  1. The link stays in access mode because both ends must be desirable
  2. The link forms a trunk because desirable actively requests trunking Correct answer.
  3. The link becomes a trunk only if 802.1Q encapsulation is manually set
  4. The link is error-disabled due to a mode mismatch

Explanation

Dynamic desirable actively attempts to negotiate a trunk, while dynamic auto passively waits for the other side to initiate. When one side is desirable, the negotiation succeeds and the link becomes a trunk. Two auto ports would remain access because neither initiates.

Question 33Routing Protocols and Switching Technologies

A router running OSPF has two equal-cost paths to a destination network. What does OSPF do by default on Cisco IOS?

  1. Drops one path and sends a summary to neighbors
  2. Installs both paths and performs equal-cost load balancing Correct answer.
  3. Installs only the path with the lowest interface cost
  4. Sends the traffic to the path with the highest router ID

Explanation

OSPF supports equal-cost multipath, and Cisco IOS installs up to four equal-cost routes by default. Traffic is distributed across those next hops. Router ID is used for tie-breaking in DR election, not for forwarding path selection.

Question 34Routing Protocols and Switching Technologies

Which OSPF network type elects a DR and BDR and sends hello packets every 10 seconds by default?

  1. Broadcast Correct answer.
  2. Point-to-multipoint
  3. Point-to-point
  4. Non-broadcast

Explanation

The broadcast network type uses multicast hellos at a 10-second interval and elects a DR and BDR. Point-to-point and point-to-multipoint types do not elect a DR. Non-broadcast also elects a DR but uses a 30-second hello interval.

Question 35Routing Protocols and Switching Technologies

Which EIGRP packet type is used to discover neighbors and to verify that a neighbor is still reachable?

  1. Reply
  2. Hello Correct answer.
  3. Update
  4. Query

Explanation

EIGRP hello packets are sent periodically to discover neighbors and maintain adjacencies. Updates carry routing information, while queries and replies are used during route recomputation. A missed hello within the hold time causes the adjacency to be torn down.

Question 36Routing Protocols and Switching Technologies

A network engineer wants a switch port to carry traffic for VLANs 10, 20, and 30 to another switch. Which configuration allows this on a single link?

  1. Configure the port as an access port in VLAN 10 only
  2. Configure the port with dynamic auto mode and no VLAN list
  3. Configure three separate access ports, one per VLAN
  4. Configure the port as a trunk and allow VLANs 10, 20, and 30 Correct answer.

Explanation

A trunk port carries multiple VLANs over one link by tagging frames with 802.1Q headers. An access port belongs to a single VLAN and cannot carry three VLANs. Dynamic auto alone does not guarantee a trunk and does not define which VLANs are allowed.

Question 37Routing Protocols and Switching Technologies

Which rapid spanning tree port role provides an alternate path to the root and can rapidly transition to forwarding when the current root port fails?

  1. Root port
  2. Designated port
  3. Alternate port Correct answer.
  4. Disabled port

Explanation

An alternate port provides a standby path to the root and normally remains in the discarding state. If the current root port fails, a suitable alternate port can become the new root port and rapidly transition to forwarding.

Question 38Routing Protocols and Switching Technologies

What is the purpose of the native VLAN on an 802.1Q trunk?

  1. It encrypts frames between switches
  2. It is the management VLAN used exclusively by STP
  3. It carries only voice traffic with priority tagging
  4. It carries untagged frames across the trunk Correct answer.

Explanation

With 802.1Q, frames in the native VLAN are transmitted untagged over the trunk. Both ends of the trunk must agree on the native VLAN to avoid VLAN mismatch issues. It is not inherently a management or voice VLAN, and it does not encrypt traffic.

Question 39Routing Protocols and Switching Technologies

Which mechanism allows a Layer 3 switch to route between VLANs without using physical router interfaces per VLAN?

  1. BPDU Guard on trunk ports
  2. Access ports bound to each VLAN
  3. PortFast on each access port
  4. Switch virtual interfaces (SVIs) Correct answer.

Explanation

An SVI is a logical Layer 3 interface associated with a VLAN, letting a multilayer switch route between VLANs internally. Access ports are Layer 2 and cannot route. PortFast and BPDU Guard are STP edge features and do not provide inter-VLAN routing.

Question 40Routing Protocols and Switching Technologies

A router has two static routes to 10.0.0.0/8: one with administrative distance 1 and one with administrative distance 5. Which route is installed in the routing table?

  1. The route with administrative distance 1 Correct answer.
  2. The route with administrative distance 5
  3. Neither route, until the distances match
  4. Both routes, with equal-cost load balancing

Explanation

When multiple routes to the same prefix exist, the router prefers the one with the lowest administrative distance. Lower AD indicates a more trusted source. Equal-cost load balancing requires matching metrics and distances, and the router does not wait for distances to match.

Question 41Routing Protocols and Switching Technologies

Which feature prevents a switch port from learning MAC addresses from more than a configured number of hosts?

  1. Port security Correct answer.
  2. BPDU Guard
  3. Dynamic ARP inspection
  4. DHCP snooping

Explanation

Port security limits the number of source MAC addresses allowed on a port and can restrict or shut down the port when exceeded. BPDU Guard acts on spanning tree BPDUs. DHCP snooping and dynamic ARP inspection protect against spoofing but do not limit MAC learning counts.

Question 42Routing Protocols and Switching Technologies

In RSTP, which port state replaces the STP blocking and listening states?

  1. Discarding Correct answer.
  2. Disabled
  3. Forwarding
  4. Learning

Explanation

RSTP consolidates STP's blocking, listening, and disabled states into a single discarding state. It retains learning and forwarding. This simplification, combined with proposal/agreement, enables faster convergence.

Question 43Routing Protocols and Switching Technologies

What does the EIGRP feasibility condition ensure when selecting a feasible successor?

  1. The neighbor has the lowest router ID
  2. The path has the fewest hops
  3. The successor has the highest bandwidth metric
  4. The reported distance is less than the current feasible distance Correct answer.

Explanation

The feasibility condition requires a neighbor's reported distance to be lower than the local feasible distance, guaranteeing a loop-free backup path. This backup is the feasible successor. Router ID and hop count are not used for this determination.

Question 44Routing Protocols and Switching Technologies

An OSPF router receives an LSA that is identical in sequence number to the one in its database. What does the router do?

  1. Increments the sequence number and floods
  2. Discards the duplicate LSA Correct answer.
  3. Requests a full database exchange
  4. Floods the LSA back to the sender

Explanation

If an incoming LSA has the same sequence number, checksum, and age, the router considers it a duplicate and silently discards it. It does not flood or request retransmission. Only newer LSAs trigger database updates and flooding.

Question 45Routing Protocols and Switching Technologies

Which protocol provides loop prevention in a Layer 2 network by exchanging BPDUs and electing a root bridge?

  1. Hot Standby Router Protocol
  2. Link Aggregation Control Protocol
  3. Virtual Router Redundancy Protocol
  4. Spanning Tree Protocol Correct answer.

Explanation

STP exchanges bridge protocol data units to elect a root bridge and block redundant paths. LACP bundles links but does not prevent loops across switches. VRRP and HSRP provide default gateway redundancy at Layer 3.

Question 46Routing Protocols and Switching Technologies

A trunk link between two switches carries a native VLAN mismatch warning. What is the most likely cause?

  1. The native VLAN is configured differently on each end of the trunk Correct answer.
  2. The trunk encapsulation types differ on each end
  3. One end is configured as an access port
  4. The allowed VLAN list is empty on one end

Explanation

Cisco switches generate a native VLAN mismatch message when the untagged VLAN differs between the two trunk endpoints. Because native VLAN frames are untagged, mismatches can leak traffic between VLANs. Encapsulation mismatch or access mode would produce different symptoms.

Question 47Routing Protocols and Switching Technologies

Which OSPF router type connects an OSPF area to the backbone area and generates Type 3 LSAs?

  1. Designated router
  2. Autonomous system boundary router
  3. Area border router Correct answer.
  4. Internal router

Explanation

An area border router has interfaces in multiple areas and injects summary LSAs (Type 3) between them. An ASBR injects external routes as Type 5 LSAs. A designated router manages adjacencies on a broadcast segment, and an internal router stays within one area.

Question 48Routing Protocols and Switching Technologies

Which statement is true about a switch port configured with PortFast?

  1. It forces the port into trunk mode
  2. It disables spanning tree on the port permanently
  3. It blocks all BPDUs received on the port
  4. It skips the listening and learning states and forwards immediately Correct answer.

Explanation

PortFast allows an edge port to transition directly to forwarding, avoiding the usual STP delay for end hosts. It does not disable STP; the port still participates. BPDU Guard, not PortFast, acts on received BPDUs, and PortFast does not change the port to trunk mode.

Question 49Routing Protocols and Switching Technologies

Which routing protocol uses the Diffusing Update Algorithm to guarantee loop-free paths at every instant?

  1. EIGRP Correct answer.
  2. IS-IS
  3. RIPv2
  4. OSPF

Explanation

EIGRP uses DUAL to compute loop-free paths and maintain feasible successors for fast reconvergence. OSPF and IS-IS use the SPF algorithm, while RIPv2 uses distance vector with split horizon and poison reverse. DUAL is specific to EIGRP.

Question 50Routing Protocols and Switching Technologies

A router running OSPF has an interface with a cost of 10 and another with a cost of 20 to reach the same network. How does OSPF decide which path to use?

  1. It selects the path with the lower total cost Correct answer.
  2. It load-balances across both paths
  3. It selects the path with the lower router ID
  4. It selects the path with the higher bandwidth interface

Explanation

OSPF computes the shortest path using cumulative interface cost, and the lowest total cost wins. Load balancing only occurs when costs are equal. Router ID is not used for path selection, and bandwidth is reflected in the cost calculation, not compared separately.