CCNA Network Services and Security Practice Test 17 — 15 Questions

Question 1

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 2

A router is performing PAT for inside users. Which detail allows multiple inside sessions to share one public IPv4 address at the same time?

Accepted Answer

Use of transport-layer port numbers to distinguish sessions. PAT works because it uses transport-layer port numbers to keep different conversations distinct even when they share the same public IP address. In plain language, the router rewrites and tracks port information so that return traffic can be matched back to the correct inside host and application session. That is what makes one public address usable for many simultaneous internal users.

This is a key difference between PAT and simple static NAT. Static NAT creates a fixed one-to-one relationship, while PAT creates many simultaneous translations differentiated by port values. The correct answer is the one that identifies port-based tracking as the reason the design scales beyond a single host.

Answer

Replacement of all MAC addresses with broadcast addresses

Answer

Automatic conversion of every subnet into a /32

Answer

Requirement that every inside host use the same private IP address

Question 3

Which two actions are reasonable examples of basic device-hardening practice?

Accepted Answer

Disable unused services or interfaces where practical. Basic hardening is about reducing unnecessary exposure and making administrative access safer. In plain language, this usually means disabling services or interfaces that are not needed and preferring secure management protocols such as SSH. These choices shrink the attack surface and improve the security of routine device administration without requiring advanced security products.

The wrong answers in hardening questions often suggest convenience at the expense of security, such as leaving insecure access methods enabled or removing authentication. CCNA-level security expects you to recognize that strong fundamentals often come from disciplined configuration choices rather than from complex tools alone.

Answer

Allow anonymous administrative login for convenience

Answer

Place all traffic in VLAN 1 so it is easier to remember

Answer

Remove authentication from VTY lines

Question 4

Which service would a client most directly rely on to convert `server.example.com` into an IP address?

Accepted Answer

DNS. The client relies on DNS for name resolution. In plain language, DNS is the service that lets devices and users use readable names instead of memorizing numeric IP addresses. When the client needs to reach `server.example.com`, DNS helps translate that hostname into the IP-related information needed for actual communication.

This is different from DHCP, which supplies address configuration, and from NTP, which synchronizes time. It is also different from ARP, which resolves local IPv4 addresses to MAC addresses. The correct answer is the one associated specifically with hostname resolution.

Answer

ARP

Answer

NTP

Answer

CDP

Question 5

Match each service to the kind of problem it most directly helps solve.

Accepted Answer

DNS - remembering IP addresses; DHCP - manual IP configuration; FTP - file transfers; SSH - encrypted remote access; RADIUS - network access; TACACS+ - device administration. DNS solves the problem of remembering IP addresses. DHCP eliminates manual IP configuration. FTP enables file transfers. SSH provides encrypted remote access. RADIUS and TACACS+ are AAA protocols, with RADIUS commonly used for network access and TACACS+ for device administration.

Answer

DNS - file transfers; DHCP - encrypted remote access; FTP - remembering IP addresses; SSH - manual IP configuration; RADIUS - device administration; TACACS+ - network access

Answer

DNS - encrypted remote access; DHCP - file transfers; FTP - manual IP configuration; SSH - remembering IP addresses; RADIUS - device administration; TACACS+ - network access

Answer

DNS - manual IP configuration; DHCP - remembering IP addresses; FTP - encrypted remote access; SSH - file transfers; RADIUS - network access; TACACS+ - device administration

Question 6

Which term in the CIA triad refers to ensuring systems and data remain accessible when needed?

Accepted Answer

Availability. The term is availability. In plain language, availability means that authorized users should be able to reach systems, services, and data when they actually need them. If a service is down, overwhelmed, or otherwise unreachable, availability has been affected. This is different from confidentiality, which focuses on preventing unauthorized disclosure, and integrity, which focuses on preventing unauthorized change.

This distinction matters because the CIA triad appears often in security foundations and exam questions. Availability is not about whether data is secret or whether it has been altered; it is about whether the service is usable. That is why availability is the best answer here.

Answer

Integrity

Answer

Accounting

Answer

Confidentiality

Question 7

A network administrator wants to secure remote CLI access to a Cisco router, moving beyond simple username/password authentication. Which approach best achieves this goal?

Accepted Answer

Use stronger or additional authentication controls to improve remote administrative access security. The goal is to strengthen authentication beyond a simple password. Cisco AAA (Authentication, Authorization, and Accounting) using TACACS+ or RADIUS provides stronger, centralized authentication. Secure Shell (SSH) with key-based or two-factor authentication also enhances security. Option A correctly describes this concept, while the other options either weaken security (B, D) or address access control via ACLs, which does not improve the authentication factor itself (C).

Answer

Replace SSH with Telnet to simplify troubleshooting

Answer

Configure an extended ACL to limit remote access to specific source IP addresses

Answer

Disable password authentication and rely solely on device location in the network

Question 8

A company wants a server on the inside network to be reachable consistently from outside using one known public IP address. Which NAT approach best fits that goal?

Accepted Answer

Static NAT. Static NAT best fits that goal because it creates a fixed, predictable one-to-one mapping between the internal server and a public address. In plain language, outside systems always know which public IP represents that server. This predictability is exactly what is needed when a service must be reachable consistently from the outside.

PAT is better suited for many outbound clients sharing one address, not for presenting one inside server with a permanent public identity. Dynamic NAT from a pool can also vary depending on design. The correct answer is the one that provides the most stable and direct one-to-one mapping.

Answer

PAT overload only

Answer

No NAT at all, because private IPv4 addresses are Internet-routable

Answer

DHCP relay

Question 9

Which option correctly matches an IP service symptom to the most likely service involved?

Accepted Answer

DNS failures prevent name resolution. DNS failures prevent name resolution because DNS is the service that translates hostnames to IP addresses. Without DNS, users cannot reach resources by name, but IP connectivity remains unaffected. This matches the symptom described in option A, making DNS the correct service.

Answer

Packet loss causes intermittent connectivity

Answer

Bandwidth congestion slows transfers

Answer

Jitter affects real-time services

Question 10

An engineer wants remote administrative access to remain available but also wants session contents protected in transit. Which management choice best supports that goal?

Accepted Answer

SSH. The best choice is SSH because it provides encrypted remote administrative access. In plain language, the engineer wants administrators to keep managing devices remotely, but without exposing credentials or session contents in clear text. SSH solves that by protecting the traffic in transit, which is why it is preferred over older plaintext protocols such as Telnet.

This is a core management-plane security principle. The goal is not to remove remote administration, but to perform it safely. The correct answer is the one that aligns with secure remote access rather than convenience at the expense of protection.

Answer

Telnet

Answer

Open wireless access

Answer

Native VLAN 1

Question 11

A router is configured for PAT using the WAN interface address. Which command element is most directly associated with allowing many internal users to share that single outside address?

Accepted Answer

overload. The `overload` element is the critical part. In plain language, that keyword tells the router to perform Port Address Translation so many inside sessions can be represented through the same outside IP address at the same time. Without overload, the router would be performing a different translation behavior and would not achieve the same many-to-one sharing model.

This is one of the most recognizable NAT design terms in CCNA because it directly distinguishes PAT from simple one-to-one translation methods. The correct answer is the part of the configuration that signals multi-session sharing through port tracking.

Answer

inside

Answer

list 1

Answer

interface

Question 12

A host reaches websites by IP address but fails when using hostnames. Which service is the strongest suspect?

Accepted Answer

DNS. The strongest suspect is DNS. In plain language, the host can already reach the remote system when given the numeric address directly, which suggests the underlying IP connectivity works. The missing piece is the translation of hostnames into IP-related information, and that is exactly the role of DNS.

This is one of the most common real troubleshooting patterns because it cleanly separates connectivity problems from name-resolution problems. If IP works but names fail, DNS becomes the most likely area to investigate.

Answer

STP

Answer

PAT

Answer

Port security

Question 13

A branch router uses PAT for Internet access. Users can browse out, but the administrator wants a specific internal web server to be reachable from outside on a consistent public address. Which design fits that requirement best?

Accepted Answer

Use static NAT for the server and PAT for general user outbound traffic.. The best design is to use static NAT for the internal web server while continuing to use PAT for general user outbound access. In plain language, PAT is ideal for many inside users sharing one public address for ordinary outbound traffic, but a server that must be reachable predictably from the outside needs a fixed public identity. Static NAT provides that one-to-one mapping.

This is a practical mixed-design scenario. The network can use PAT for user convenience and address conservation while still reserving a stable translation for a server that external clients need to find reliably. The correct answer recognizes that different NAT methods can serve different purposes in the same environment.

Answer

Use only PAT for everything, including predictable outside server reachability.

Answer

Disable NAT entirely because private IPv4 addresses are Internet-routable.

Answer

Use DHCP relay to publish the server externally.

Question 14

Match each NAT term to its most accurate description.

Accepted Answer

Inside Local: The IP address of an internal host as seen from inside the network.. NAT terms describe address perspectives: Inside Local is the internal host's IP, Inside Global is its external IP, Outside Local is the external host's IP seen internally, Outside Global is its actual external IP, Static NAT provides permanent mapping, and Dynamic NAT uses a pool.

Answer

Inside Local: The IP address of an external host as seen from inside the network.

Answer

Inside Local: The IP address of an internal host as seen from outside the network.

Answer

Inside Local: The IP address of an external host as seen from outside the network.

Question 15

A host receives its IP address automatically but cannot resolve hostnames. Which additional service information is most likely missing from its configuration?

Accepted Answer

A DNS server address. If the host receives an IP address but cannot resolve hostnames, the most likely missing information is a DNS server setting. In plain language, the device has enough configuration to join the network but not enough to ask where hostnames map in IP terms. DHCP can provide this DNS server information automatically, and if it is missing, the host may still communicate by IP while failing on names.

This is a common service-troubleshooting pattern because it separates address configuration from name resolution. The correct answer is the missing DNS-related setting rather than the IP address itself or the subnet mask.

Answer

A new MAC address

Answer

A trunk native VLAN

Answer

An OSPF router ID