CCNA Network Services and Security Practice Test 18 — 15 Questions

Question 1

A router is configured with a static NAT mapping for an internal server. What is the main operational advantage of this design for outside clients?

Accepted Answer

The server is represented by a fixed public address that outside clients can reach predictably. The main operational advantage is predictability. In plain language, outside clients always know which public IP address represents the internal server. That stable one-to-one mapping makes the server easier to reach consistently from external networks. This is exactly why static NAT is commonly used for inside services that need outside reachability.

This differs from PAT, which is optimized for many outbound user sessions sharing fewer public addresses. Static NAT is valuable when a specific device or service must have a stable external identity.

Answer

The server automatically shares its public address with all inside users through overload

Answer

The server no longer needs an IP address on the internal network

Answer

The mapping removes the need for routing to the server

Question 2

Which two statements accurately describe DNS in normal network operation?

Accepted Answer

DNS helps resolve hostnames into IP-related information.. DNS helps translate human-friendly names into IP-related information. In plain language, it allows users and applications to work with names instead of memorizing numeric addresses. It also means that a network can change the underlying IP address of a service while keeping the public-facing name the same. DNS is therefore both a usability service and an important abstraction layer.

The wrong answers often confuse DNS with DHCP or routing protocols. The two correct answers are the ones that preserve its role in name resolution and human-friendly network use.

Answer

DNS dynamically assigns host IP addresses like DHCP.

Answer

DNS replaces the need for default gateways.

Answer

DNS is the spanning-tree protocol used on VLAN trunks.

Question 3

A switchport is configured with sticky MAC learning and a maximum secure MAC value of 2. What is the main benefit of sticky learning in this situation?

Accepted Answer

It allows secure MAC addresses to be learned dynamically and used by port security.. Sticky MAC learning allows the switch to learn secure MAC addresses dynamically and treat them as port-security entries without the administrator typing them manually. In plain language, it combines some of the convenience of automatic learning with the control of port security. If the configuration is later saved, those learned entries can become persistent.

This is a common CCNA port-security concept because it shows how sticky learning works with, not instead of, port security. The correct answer is the one focused on dynamic secure learning and convenience, not on disabling the maximum limit or turning the port into a trunk.

Answer

It removes the maximum secure MAC limit automatically.

Answer

It converts the port into a trunk after two MAC addresses are learned.

Answer

It disables port security after the first reboot.

Question 4

Why is NTP especially useful when devices send logs to a centralized Syslog server?

Accepted Answer

It helps align device clocks so centralized log timestamps can be correlated more accurately.. NTP is especially useful because synchronized clocks make the log timestamps more meaningful and easier to correlate. In plain language, if each device thinks the current time is different, the sequence of events in the centralized log becomes confusing. NTP helps align time across devices so the logs tell a more accurate story.

This is an operational best practice. Syslog collects the messages, and NTP makes their timing consistent. The correct answer is the one focused on timestamp correlation.

Answer

It assigns the Syslog server an IP address.

Answer

It replaces the need for a Syslog server.

Answer

It encrypts every Syslog message automatically.

Question 5

An internal server must always be reachable from outside using the same public IP address. Which translation approach is most appropriate?

Accepted Answer

Static NAT. A static NAT mapping is the most appropriate approach. In plain language, the outside world needs a stable public address that always represents the same internal server. Static NAT provides that fixed one-to-one relationship, which makes the service reachable predictably.

PAT is better suited for many outbound users sharing one public address, not for presenting one inside server with a consistent external identity. The correct answer is the one that provides a permanent mapping.

Answer

PAT overload

Answer

No NAT

Answer

DHCP relay

Question 6

A small office uses PAT for user Internet access. What mechanism does PAT use to allow many users to share one public address while keeping their sessions distinct?

Accepted Answer

Use transport-layer port values to distinguish multiple inside sessions behind one outside address.. PAT (Port Address Translation) distinguishes multiple inside sessions by rewriting the source port number for each connection while using the same public IP address. This transport-layer port translation allows many internal hosts to share one outside address without conflict. The correct answer identifies the use of port numbers, which is the core mechanism. Increasing the NAT pool or using static NAT would not enable sharing of a single public address. Changing private IPs to be identical or disabling routes are irrelevant to PAT's operation.

Answer

Convert all inside hosts to the same private IP address.

Answer

Increase the size of the NAT pool to include multiple public addresses.

Answer

Configure static NAT mappings for each inside host.

Question 7

A user can reach a remote web server by IP address but not by hostname. Which service should be checked first?

Accepted Answer

DNS. DNS should be checked first. In plain language, the path to the server appears to work because the user can reach it by numeric address. The missing function is the translation from hostname to IP-related information, and that is exactly what DNS provides.

This is one of the clearest service-troubleshooting patterns in networking. If IP works but the name fails, DNS becomes the strongest first suspect. The correct answer is therefore the name-resolution service rather than a routing or switching feature.

Answer

STP

Answer

PAT

Answer

Port security

Question 8

Select the options that correctly pair the security principle or control with its meaning.

Accepted Answer

Confidentiality ensures that data is accessible only to authorized users.. Confidentiality ensures data is accessible only to authorized users; integrity ensures data accuracy and trustworthiness (not availability); non-repudiation ensures accountability by preventing denial of actions; authorization grants permissions (not identity verification, which is authentication). Option B is wrong because integrity is about data correctness, not availability. Option D is wrong because authorization determines permissions, while authentication verifies identity.

Answer

Integrity ensures that data is always available when needed.

Answer

Authorization verifies the identity of a user or device.

Question 9

A company wants internal users to share one public IPv4 address for outbound Internet access, while keeping sessions separate. Which NAT approach best meets that requirement?

Accepted Answer

PAT overload. PAT is the correct approach because it allows many internal sessions to share one outside IPv4 address while distinguishing them by port numbers. In plain language, PAT gives the office an efficient many-to-one translation model that works well for ordinary user Internet access when public addresses are limited.

This is different from static NAT, which gives a fixed one-to-one mapping, and from dynamic NAT pools that usually rely on multiple public addresses. The correct answer is the translation method designed specifically for shared public-address use across many sessions.

Answer

Static NAT only

Answer

No NAT, because private IPv4 addresses are Internet-routable

Answer

DHCP relay

Question 10

A host has a valid IP address and subnet mask from DHCP but cannot reach remote networks because no gateway was provided. What is the best explanation?

Accepted Answer

The host has no next-hop gateway for traffic destined outside its local subnet.. The best explanation is that the host has no next-hop path for off-subnet traffic. In plain language, the device knows what its own local network looks like, but it does not know where to send packets when the destination is outside that local range. Without a default gateway, remote communication usually fails even though local communication can still work.

This is a core host-configuration concept. The correct answer is the one focused on the absence of a next hop for remote destinations.

Answer

The host cannot use ARP on the local network anymore.

Answer

The host automatically becomes part of every remote subnet.

Answer

The host must convert its access port into a trunk.

Question 11

A router is configured with PAT for inside users. Which symptom most strongly suggests the NAT inside/outside roles are reversed on the interfaces?

Accepted Answer

Outbound traffic still shows private inside source addresses where translated public addresses should appear.. When NAT inside/outside roles are reversed, the router applies translation logic in the wrong direction, causing traffic from the inside network to leave the outside interface with untranslated private source addresses. The correct answer (A) directly demonstrates this failure: outbound traffic still shows private IPs where a public address should appear after PAT. The other options describe symptoms that could occur with other NAT misconfigurations but do not strongly indicate reversed roles: an empty translation table (B) suggests no NAT processing at all, possibly due to missing ACL or overload configuration; total lack of internet access (C) may result from many connectivity issues, not specifically reversed interface roles; and external hosts reaching internal servers by private IP (D) points more to a missing or incorrect static NAT rule rather than direction reversal.

Answer

The NAT translation table is empty even though internal users are browsing the internet.

Answer

Internal hosts cannot reach the internet at all.

Answer

External hosts can connect to internal servers using their private IP addresses.

Question 12

Why is the combination of strong authentication and centralized logging generally better than using either one alone?

Accepted Answer

Authentication helps prevent unauthorized access, 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 activity across the environment. In plain language, one control focuses more on prevention, while the other improves visibility and accountability. Together they create a stronger security posture than either one alone.

This is an important design mindset. Security is stronger when controls complement each other instead of trying to solve every problem with one mechanism. The correct answer is the one focused on prevention plus visibility.

Answer

They are redundant because both perform exactly the same function.

Answer

Centralized logging makes authentication unnecessary.

Answer

Strong authentication removes the need for device event records.

Question 13

A host can reach remote websites by IP address but fails when using their hostnames. Which missing configuration item is the strongest suspect?

Accepted Answer

A DNS server address. When a host can reach remote websites by IP address but not by hostname, the issue is that the host cannot resolve the hostname to an IP address. DNS (Domain Name System) is responsible for this resolution, and if the DNS server address is missing or misconfigured on the host, name resolution fails. This is the strongest suspect because all other network connectivity (routing, switching) is functional, as proven by successful IP-based access.

Answer

A new MAC address

Answer

A trunk native VLAN

Answer

An OSPF router ID

Question 14

Which two statements accurately describe DNS in everyday network use?

Accepted Answer

DNS helps resolve hostnames into IP-related information.. DNS translates human-friendly hostnames into IP-related information, making network services more accessible by name rather than numeric addresses. Option A is correct because DNS resolves names to IP addresses. Option B is correct because using names improves usability and allows underlying IP changes without user disruption. Option C is incorrect because IP address assignment is a DHCP function, not DNS. Option D is incorrect because subnet masks are part of IP addressing and routing, unrelated to DNS name resolution. Option E is incorrect because STP (Spanning Tree Protocol) elects a root bridge for loop-free topology, which is unrelated to DNS.

Answer

DNS automatically assigns IP addresses to hosts.

Answer

DNS replaces the need for subnet masks.

Answer

DNS elects the STP root bridge.

Question 15

Users on the inside network can browse the web, but the company now needs an internal web server at 192.168.10.50 to be reachable consistently from outside using one public IP address. Which design is most appropriate?

Accepted Answer

Use static NAT for the server and continue using PAT for user outbound access.. The best design is static NAT for the server while continuing to use PAT for general user outbound traffic. In plain language, user browsing and server publishing are two different requirements. PAT is great for letting many inside users share one public address for outbound access. But a server that outside clients must find reliably needs a fixed one-to-one public identity. That is exactly what static NAT provides.

This is an important design distinction. PAT solves address conservation for many clients. Static NAT solves predictability for inbound access to a specific internal system. The strongest answer is the one that uses each NAT method for the job it fits best.

Answer

Use PAT only for everything, including the published server.

Answer

Disable NAT because private IPv4 addresses are Internet-routable.

Answer

Use DHCP relay for the server to make it reachable from outside.