CCNA Practice Test 27 — 15 Questions

Question 1

A host at 192.168.50.10/24 needs to send traffic to 192.168.60.20. Which MAC address will it normally place in the Ethernet destination field for the first frame?

Accepted Answer

The MAC address of its configured default gateway. When a host wants to send traffic to a different IP subnet, it does not send the frame directly to the remote device’s MAC address. In plain language, the host knows the destination IP is off its local network, so it hands the traffic to the local router. That means the Ethernet frame is addressed to the default gateway’s MAC address, while the IP packet inside still carries the final remote IP destination.

A host uses ARP to learn MAC addresses on its own LAN. Since the remote host is not local, the sender does not ARP for the remote host’s MAC. Instead, it ARPs for the gateway interface on the same subnet.

Answer

The MAC address of the remote host at 192.168.60.20

Answer

The broadcast MAC address only

Answer

Its own source MAC address

Question 2

Which TWO statements correctly describe the configuration and effect of Root Guard and BPDU Guard on a Cisco switch?

Accepted Answer

Root Guard is configured on a per-port basis and causes the port to become root-inconsistent if a superior BPDU is received.. Root Guard is configured per interface using the 'spanning-tree guard root' command. When a port with Root Guard enabled receives a superior BPDU (one that would cause the switch to become a non-root bridge), the port is placed into a root-inconsistent state, effectively blocking traffic on that port and preventing the switch from accepting a new root bridge from that direction. This protects the spanning-tree topology from unauthorized or misconfigured switches attempting to become the root bridge. Option D is correct because BPDU Guard is commonly enabled on ports with PortFast (typically access ports connected to end devices). When a BPDU is received on such a port, BPDU Guard places the port into errdisable state, preventing potential bridging loops that could result from an unauthorized switch connecting to the network. Option B is incorrect because BPDU Guard does not prevent loops by disabling a trunk port; it is typically used on access ports (often with PortFast) and disables the port upon receiving any BPDU, not just on trunk ports. Option C is incorrect because Root Guard places the port into root-inconsistent state (not errdisable) when a superior BPDU is received; BPDU Guard uses errdisable. Option E is incorrect because neither Root Guard nor BPDU Guard filters BPDUs; Root Guard reacts to superior BPDUs by blocking the port, and BPDU Guard reacts to any BPDU by disabling the port. Both features allow BPDUs to be processed but then take action based on the received BPDUs.

Answer

BPDU Guard prevents loops by disabling a trunk port that receives a BPDU from an unauthorized switch.

Answer

Root Guard places a port in errdisable state when a superior BPDU is received.

Answer

Both Root Guard and BPDU Guard filter BPDUs to prevent them from being processed by the switch CPU.

Question 3

A multilayer switch has working SVIs for VLAN 10 and VLAN 20, but traffic between the VLANs fails. Hosts can ping their own gateway interfaces. Which misconfiguration is most strongly suggested if the SVIs themselves are correct?

Accepted Answer

IP routing is not enabled on the multilayer switch.. IP routing is not enabled. The switch can ping SVIs locally because they are directly connected, but without `ip routing`, it cannot forward packets between VLANs. Option B is wrong because different VLANs require different subnets for routing. Option C is wrong because access ports do not need to be trunks; SVIs handle routing at Layer 3. Option D is wrong because the wireless controller does not provide the default gateway for wired VLAN routing; the SVI does.

Answer

Both VLANs need to use the same IP subnet.

Answer

All access ports must be converted into trunks.

Answer

The wireless controller must provide the default gateway.

Question 4

A router has routes to 192.168.0.0/16 and 192.168.100.0/24. Which route is used for traffic to 192.168.100.77?

Accepted Answer

192.168.100.0/24. The route to 192.168.100.0/24 is used because it is more specific. In plain language, even though the /16 route covers a large address range that includes the destination, the /24 route describes the destination network more precisely. Longest-prefix match therefore prefers the /24.

This is a basic but critical routing-table concept. The router does not choose the broader route when a narrower one matches the same destination.

Answer

192.168.0.0/16

Answer

Both routes are discarded because they overlap.

Answer

The default route is preferred if present.

Question 5

A network operations team is implementing an automated system to detect and remediate interface flapping on core switches. The system must be able to query the network device for interface status and execute commands to disable or reconfigure the interface if a pattern of flapping is detected. Which protocol or technology enables the system to programmatically interact with the network device for both monitoring and configuration changes?

Accepted Answer

NETCONF. NETCONF is the correct choice because it is a standardized network configuration protocol that allows automated systems to retrieve operational data and push configuration changes securely. In this scenario, the system would use NETCONF to query interface status and then apply remediation configurations. SNMP can monitor but has limited configuration capabilities, CLI scripting is non-programmatic and error-prone, and Syslog is only for logging.

Answer

SNMP

Answer

CLI scripting

Answer

Syslog

Question 6

A static default route is configured with an administrative distance of 250. What is the most likely design intention?

Accepted Answer

To keep the route as a backup of last resort behind normal learned routes. The design intention is to make the static default route a very low-priority backup path. In plain language, the administrator wants the route to exist only as a last resort behind almost any normal learned path. By assigning such a high administrative distance, the route stays out of the active table unless better routes disappear.

This is a floating-static design concept. The route is not meant to be primary. It is intentionally configured to sit in reserve and become relevant only during failure conditions or severe loss of normal routing information.

Answer

To make the route override all dynamic routing immediately

Answer

To disable default routing entirely

Answer

To convert the default route into a host route

Question 7

A network technician is troubleshooting a connectivity issue where a user's email client cannot send messages, but the client can receive emails. The technician uses a protocol analyzer and sees that the client is successfully resolving the mail server's domain name to an IP address and establishing a TCP connection, but the server responds with an application-layer error. At which layers of the OSI model are the problem and the successful operations occurring, respectively?

Accepted Answer

The problem is at the Application layer (Layer 7); successful operations are at the Application layer (Layer 7) and Transport layer (Layer 4).. The problem is at the Application layer (Layer 7) because the email client can resolve the domain name (DNS, Layer 7), establish a TCP connection (Transport layer, Layer 4), but the mail server returns an application-layer error (e.g., SMTP 550 or 554), indicating the issue lies in the email protocol itself (e.g., authentication failure, mailbox full, or rejected sender). Successful operations include DNS resolution (Application layer) and TCP three-way handshake (Transport layer), confirming layers 7 and 4 are functioning correctly.

Answer

The problem is at the Transport layer (Layer 4); successful operations are at the Application layer (Layer 7) only.

Answer

The problem is at the Network layer (Layer 3); successful operations are at the Data Link layer (Layer 2) and Physical layer (Layer 1).

Answer

The problem is at the Presentation layer (Layer 6); successful operations are at the Session layer (Layer 5) and Transport layer (Layer 4).

Question 8

Which TWO statements correctly describe the configuration and use of a voice VLAN on a Cisco switch port?

Accepted Answer

When a voice VLAN is configured, the switch port operates in two VLANs: one for data and one for voice traffic.. When a voice VLAN is configured on a Cisco switch port, the port operates in two separate VLANs simultaneously: one for data traffic (the access VLAN) and one for voice traffic (the voice VLAN). This is achieved using the 'switchport voice vlan' command, which allows the switch to tag voice frames with the voice VLAN ID while leaving data frames untagged (or tagged with the access VLAN). This separation ensures that voice traffic receives appropriate QoS treatment and is isolated from data traffic.

Answer

The voice VLAN is configured using the 'switchport mode trunk' command.

Answer

The voice VLAN must be the same as the native VLAN on the trunk link.

Answer

The data VLAN and voice VLAN must be in the same IP subnet.

Question 9

Match each common automation term to its most accurate meaning.

Accepted Answer

Infrastructure as Code: Managing infrastructure through machine-readable definition files. Infrastructure as Code (IaC) refers to managing and provisioning infrastructure through machine-readable definition files, enabling automation and version control. Idempotence means that performing the same operation multiple times results in the same state, ensuring consistency. The declarative model allows the user to define the desired end state, and the system automatically determines how to achieve it. In contrast, the imperative model requires the user to specify step-by-step instructions to reach the desired state. These four terms are fundamental to understanding network automation approaches.

Question 10

Match each automation-related term to the description that best fits it.

Accepted Answer

Idempotent: An operation that can be applied multiple times without changing the result beyond the initial application.. The question requires matching automation-related terms to their correct descriptions. Idempotent means that an operation can be applied multiple times without changing the result after the first application. Declarative is a style where the user defines the desired state and the system determines the steps to achieve it. Imperative is a style where explicit step-by-step instructions are given. Orchestration refers to the automated coordination of multiple systems or services to complete a workflow. Each description aligns precisely with these concepts.

Question 11

Match each Layer 2 protection feature to its most accurate purpose.

Accepted Answer

Storm Control: Limits excessive broadcast, multicast, or unicast traffic to prevent network storms.. Storm Control limits excessive traffic. Port Security limits MAC addresses. DHCP Snooping blocks unauthorized DHCP servers. DAI validates ARP packets. IP Source Guard filters IP traffic based on DHCP snooping. 802.1X authenticates devices before granting access.

Answer

Storm Control: Authenticates devices before granting network access.

Answer

Storm Control: Validates ARP packets to prevent ARP spoofing attacks.

Answer

Storm Control: Filters IP traffic based on DHCP snooping bindings.

Question 12

Which TWO statements accurately describe the encapsulation process and PDU naming across the OSI and TCP/IP models?

Accepted Answer

In the OSI model, the Network layer encapsulates data into packets, while in the TCP/IP model the Internet layer performs the same function.. The OSI Network layer and the TCP/IP Internet layer both encapsulate transport layer segments or datagrams into packets by adding a Layer 3 header (e.g., IP header). This is the fundamental encapsulation step where logical addressing is applied, and the resulting PDU is called a packet in both models. The function is identical despite the different layer names.

Answer

At the Transport layer, the TCP/IP model uses segments, while the OSI model uses packets.

Answer

Encapsulation adds headers and trailers at each layer, so the PDU size decreases as data moves down the stack.

Answer

The OSI model's Session layer is responsible for end-to-end flow control using TCP segments, while the TCP/IP model combines this into the Application layer.

Question 13

A user connects a small unmanaged switch to an access port, and the port immediately transitions to err-disabled. Which feature most likely caused this behavior?

Accepted Answer

BPDU Guard. BPDU Guard is the correct answer because it is specifically designed to protect access ports configured with PortFast. When an unauthorized switch is connected to such a port, BPDU Guard detects the incoming BPDU and immediately places the port into err-disabled state, preventing potential loops or topology changes. UDLD aggressive detects unidirectional links but does not cause err-disabled due to BPDU reception. Root guard blocks ports that attempt to become the root bridge by placing them in root-inconsistent state (not err-disabled). Loop guard prevents alternate/root ports from becoming designated in the absence of BPDUs, putting the port into loop-inconsistent state, again not err-disabled.

Answer

UDLD aggressive

Answer

Root guard

Answer

Loop guard

Question 14

Why is route summarization often useful at distribution or area boundaries in larger networks?

Accepted Answer

It reduces the number of route advertisements by combining multiple specific prefixes. Route summarization is useful there because it reduces the number of specific prefixes that must be advertised upstream or across boundaries. In plain language, instead of sending many small route entries, the network can often advertise one broader summary that represents them collectively. This helps control routing-table growth and can make the design more scalable and easier to manage.

Summarization does not eliminate the need for routing detail inside the local area, but it can simplify what needs to be shared outward. That is why it is especially valuable at aggregation points such as distribution layers or area boundaries.

Answer

It forces all users into the same VLAN

Answer

It automatically encrypts routing protocols

Answer

It removes the need for IP addressing

Question 15

Match each IPv6 concept to its most accurate description.

Accepted Answer

IPv6 address: 128-bit identifier for network interfaces. These pairings accurately define key IPv6 concepts.