CCNA Network Services and Security Practice Test 19 — 15 Questions

Question 1

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 2

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 3

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 4

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 5

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 6

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 7

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

Question 8

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 9

Which two statements accurately describe DNS in normal network operation?

Accepted Answer

DNS helps resolve hostnames into IP-related information.. Option A is correct because DNS (Domain Name System) performs name resolution, translating human-readable hostnames such as www.example.com into IP-related information like A records (IPv4 addresses) and AAAA records (IPv6 addresses). Option B is correct because this name-to-address mapping lets users reference hosts by meaningful names instead of memorizing raw IP addresses, which is the core usability benefit of DNS in normal network operation. Option C is incorrect because dynamic IP address assignment is the function of DHCP (Dynamic Host Configuration Protocol), not DNS, which resolves names rather than leasing addresses. Option D is incorrect because default gateways are configured on hosts to route traffic off the local subnet, and DNS does not replace that routing function. Option E is incorrect because the Spanning Tree Protocol (STP, IEEE 802.1D) prevents Layer 2 loops on switches and VLAN trunks, and has nothing to do with DNS.

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 10

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 11

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 12

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 13

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 14

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 15

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.