CCNA Practice Exam 54 — 20 Questions

Question 1

Exhibit: PCs in VLAN 20 are not receiving addresses from a DHCP server in another subnet. The switch SVI for VLAN 20 is up, and routing is working. Which configuration is most likely missing on the gateway for VLAN 20?

Accepted Answer

ip helper-address 10.99.99.10. DHCP Discover messages are broadcasts and do not cross routers by default. An ip helper-address on the client gateway interface relays those requests to a remote DHCP server.

Answer

ip default-gateway 10.20.20.1

Answer

switchport trunk allowed vlan 20

Answer

spanning-tree portfast default

Question 2

Exhibit: An engineer wants a device to send only warning messages and more critical events to a syslog server. Which logging level should be configured?

Accepted Answer

logging trap warnings. Syslog severity levels include lower numbers for more severe events. Warning is level 4, so setting logging trap warnings sends level 4, 3, 2, 1, and 0 messages.

Answer

logging trap debugging

Answer

logging trap notifications

Answer

logging trap informational

Question 3

Exhibit: A user can ping 8.8.8.8 successfully but cannot browse to www.example.com by name. Which service is the most likely failing component?

Accepted Answer

DNS. If connectivity to an IP address works but name-based access fails, the path is up and the problem is usually name resolution. DNS is the service that translates hostnames into IP addresses.

Answer

NTP

Answer

Syslog

Answer

CDP

Question 4

A branch router should automatically learn the IP address of a time source so logs from all devices show matching timestamps. Which service provides that function?

Accepted Answer

NTP. NTP synchronizes clocks across network devices. When timestamps line up, syslog messages and troubleshooting output become much more useful.

Answer

DNS

Answer

TFTP

Answer

NetFlow

Question 5

A router is configured for PAT overload. What does the inside global address represent for an internal PC?

Accepted Answer

The public address that represents the internal PC to external networks. With NAT overload, the inside local address is the private address on the internal host. The inside global is the translated public address that represents that inside host to the outside network.

Answer

The private IP address assigned to the internal PC

Answer

The remote server address as seen from the inside host

Answer

The MAC address of the outside interface

Question 6

Which protocol is used to resolve a hostname such as www.example.com into an IP address?

Accepted Answer

DNS. DNS resolves names to addresses. DHCP hands out addressing parameters, NTP synchronizes time, and SNMP is used for management and monitoring.

Answer

DHCP

Answer

NTP

Answer

SNMP

Question 7

Users can browse websites by IP address but not by hostname. The default gateway is reachable and general internet connectivity works. Which two causes are the most likely?

Accepted Answer

The clients are missing a valid DNS server setting. If IP connectivity works but hostnames fail, the problem is usually DNS configuration or DNS reachability, not general routing.

Answer

The routers are missing NTP configuration

Answer

The switch access ports should be changed to dynamic desirable

Question 8

A network team wants to collect flow-level traffic statistics from routers to identify top talkers and bandwidth consumers. Which two statements about NetFlow are correct?

Accepted Answer

It summarizes traffic into flows instead of capturing every packet payload. NetFlow provides visibility into who is talking to whom, with what protocols and volume, making it valuable for capacity planning, troubleshooting, and security analysis.

Answer

It is primarily used to distribute time from an authoritative clock

Answer

It replaces routing protocols by advertising reachability information

Question 9

A small office wants branch routers to automatically hand out IP addresses, default gateway values, and DNS servers to clients. Which service should be configured?

Accepted Answer

DHCP. DHCP is built for this exact job. It centrally provides addressing details so endpoints do not need to be configured by hand.

Answer

DNS

Answer

NTP

Answer

TACACS+

Question 10

Why is the combination of strong authentication and centralized logging better than either control by itself?

Accepted Answer

Authentication improves prevention, while centralized logging improves visibility and investigation.. The combination is better because strong authentication helps prevent unauthorized access, while centralized logging helps detect, review, and investigate what happened across the environment. In practical terms, one control is stronger on prevention, and the other is stronger on visibility and accountability. Together they provide broader protection than either one alone.

This reflects a real security principle: mature security depends on layers of control, not one mechanism trying to do every job.

Answer

They are redundant because both perform exactly the same task.

Answer

Centralized logging makes authentication unnecessary.

Answer

Strong authentication removes the need for any event records.

Question 11

A router is configured as a DHCP server for VLAN 20. Clients on the VLAN can reach the default gateway, but they do not receive leases. Which two configuration issues on the router would directly prevent successful address assignment?

Accepted Answer

The excluded-address range removes the entire usable subnet. The router can serve DHCP locally without an ip helper-address. The real problem is that the excluded-address range consumes every usable host address, leaving the pool with no assignable leases.

Answer

The DHCP pool is missing a dns-server statement

Answer

The subinterface lacks an ip helper-address

Question 12

Exhibit: A client can ping 8.8.8.8 but cannot browse to www.example.com. Which service is most likely failing?

Accepted Answer

DNS. The client has IP connectivity because it can reach 8.8.8.8 directly. The problem appears only when using a hostname, which points to a DNS resolution issue rather than a routing issue.

Answer

NTP

Answer

DHCP snooping

Answer

HSRP

Question 13

Exhibit: A network engineer wants to identify which applications are consuming most WAN bandwidth over time. Which feature should be enabled on the router?

Accepted Answer

NetFlow. NetFlow records conversations and traffic characteristics so an external collector can analyze top talkers, protocols, and usage trends. Syslog and SNMP have different purposes.

Answer

NTP authentication

Answer

DNS forwarding

Answer

DHCP snooping

Question 14

Why is NTP especially valuable when a network uses centralized Syslog servers?

Accepted Answer

Because synchronized clocks make log timestamps easier to correlate across devices. NTP is especially valuable because centralized logs are much easier to interpret when device clocks are synchronized. In plain language, if multiple routers and switches send messages to one logging server but each device believes a different time, the event sequence becomes confusing. NTP helps align those clocks so the timestamps in the logs are consistent and the team can reconstruct incidents more accurately.

This is a practical operations concept rather than a syntax question. Syslog solves the collection problem, and NTP solves the time-correlation problem. Together they make logs more useful than either one alone. That is why the best answer focuses on timestamp consistency rather than on routing, VLAN, or NAT behavior.

Answer

Because NTP converts Syslog into a routing protocol

Answer

Because NTP automatically creates DHCP pools

Answer

Because NTP eliminates the need for a Syslog server

Question 15

Why is NTP especially valuable when a company uses a centralized Syslog server?

Accepted Answer

It synchronizes device clocks so centralized log timestamps can be correlated accurately.. NTP is especially valuable because it aligns device clocks, which makes centralized log timestamps much easier to interpret. In practical terms, if devices disagree on time, the combined log stream becomes harder to trust and correlate. NTP improves the timeline accuracy of operational and security analysis.

This is why NTP and Syslog are often discussed together. One centralizes events, and the other makes those events easier to line up correctly.

Answer

It assigns the Syslog server its IP address.

Answer

It replaces the need for Syslog entirely.

Answer

It encrypts all Syslog messages automatically.

Question 16

Two switches are connected by an 802.1Q trunk. CDP reports a native VLAN mismatch. Which issue is most likely to appear because of this?

Accepted Answer

Untagged traffic may be placed into different VLANs on each switch.. A native VLAN mismatch can cause untagged traffic sent on one side to be placed into a different VLAN on the other side. That leads to confusing connectivity issues and can also create security concerns. It does not automatically disable the trunk.

Answer

All tagged traffic on the trunk is dropped immediately.

Answer

STP is disabled on the trunk link.

Answer

The trunk automatically converts to an access port.

Question 17

R1 has the following routes installed:

O    10.10.10.0/24 via 192.0.2.2
S    10.10.10.128/25 via 198.51.100.2
S*   0.0.0.0/0 via 203.0.113.1

A packet destined for 10.10.10.200 arrives at R1. Which route is used?

Accepted Answer

The static route to 10.10.10.128/25 via 198.51.100.2. Routers forward using longest prefix match first. Even though the OSPF /24 exists, the static /25 is more specific and covers 10.10.10.200, so the packet is sent via 198.51.100.2. The default route is used only when nothing more specific matches.

Answer

The OSPF route to 10.10.10.0/24 via 192.0.2.2

Answer

The default route via 203.0.113.1

Answer

The packet is dropped because OSPF routes cannot overlap with static routes.

Question 18

A branch router has only one WAN link connected to an Ethernet handoff from the provider. Which static default route is generally the better choice?

Accepted Answer

ip route 0.0.0.0 0.0.0.0 198.51.100.1. On multiaccess Ethernet, pointing the default route to a next-hop IP address is usually cleaner because the router can resolve the next hop with ARP. Using only the exit interface on Ethernet can make the router treat many destinations as directly connected and trigger unnecessary ARP behavior.

Answer

ip route 0.0.0.0 0.0.0.0 GigabitEthernet0/0

Answer

ip route 255.255.255.255 255.255.255.255 198.51.100.1

Answer

No static default route should ever be used on Ethernet.

Question 19

A user reports that their desk port stopped working immediately after they connected a small switch. The interface shows err-disabled, and the log mentions BPDU Guard. What most likely happened?

Accepted Answer

The port received a BPDU and BPDU Guard shut it down.. BPDU Guard is commonly enabled on PortFast access ports to protect the topology. If the port receives a BPDU, the switch assumes another switch may have been connected and places the port into err-disabled state. That is exactly the protective behavior you want at the edge.

Answer

DHCP snooping blocked the user's ARP requests.

Answer

Port security moved the port to protect mode.

Answer

The trunk native VLAN matched incorrectly.

Question 20

R1 learns three OSPF routes to different destinations:

O 10.10.10.0/24
O IA 10.20.20.0/24
O E2 10.30.30.0/24

Which statement is correct about these route types?

Accepted Answer

O E2 is an OSPF external type 2 route.. An O route is intra-area, O IA is interarea, and O E2 is an external type 2 route redistributed into OSPF. The codes describe route origin, not just preference. CCNA expects you to identify them quickly when reading the routing table.

Answer

O IA is an external route redistributed from another routing protocol.

Answer

O means the route was learned through EIGRP.

Answer

All three routes were learned from the same OSPF area type.