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2237 questions

Question 81Question

During a security audit of network infrastructure management practices, an auditor notes that switch management sessions rely on a protocol that encrypts only the password field within packet headers and combines authentication and authorization into a single service over UDP. To achieve full payload encryption, command-by-command authorization decoupling, and reliable connection-oriented transport on port 49, which protocol should be deployed?

Show answer & explanation

Answer: TACACS+

Answer

TACACS+ (Terminal Access Controller Access-Control System Plus) should be deployed because it operates over TCP port 49, encrypts the entire packet payload, and decouples authentication and authorization into distinct modular processes.
TACACS+ satisfies all requirement criteria: it uses connection-oriented TCP port 49, encrypts the complete packet payload (protecting administrative command traffic), and separates authentication, authorization, and accounting into distinct modular components.

Step-by-Step Solution

1
Evaluate transport layer and encryption scope requirements.
The requirement specifies full packet payload encryption and connection-oriented transport over TCP port 49.
TACACS+ utilizes TCP port 49 and encrypts the entire body of the packet, whereas RADIUS only encrypts the password attribute over UDP.
2
Analyze AAA service architectural separation.
The targeted protocol must decouple authentication from authorization functionality.
TACACS+ separates AAA functions, allowing granular authorization of individual admin commands independently of authentication, whereas RADIUS combines authentication and authorization.

Key Concept

RADIUS vs. TACACS+ Feature & Architectural Differentiation
Estimated Time:1m 15s
Question 82Question

A network operations engineer is investigating a routing failure following an unexpected failover between two redundant core routers. During the incident analysis, the engineer suspects that client workstations were incorrectly configured with the physical interface IP address of a single router rather than the shared Virtual IP (VIP) designated for the First Hop Redundancy Protocol (FHRP) group. To validate the authoritative VIP allocations, Layer 3 subnet boundaries, and associated VLAN identifiers without relying on live device configurations, which network documentation artifact should the engineer consult?

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Answer: Logical network topology diagram paired with an IP address management baseline document

Answer

Logical network topology diagram paired with an IP address management baseline document
The correct option is the logical network topology diagram combined with an IP address management baseline. Logical diagrams illustrate how data flows through a network by documenting Layer 3 IP addressing, network subnets, VLAN boundaries, and virtual interface configurations such as First Hop Redundancy Protocol (FHRP) Virtual IPs (VIPs).

Step-by-Step Solution

1
Analyze the technical requirements of the scenario.
The investigation requires locating Layer 3 IP subnets, VLAN assignments, and FHRP Virtual IP (VIP) gateway configurations.
Resolving default gateway unreachability due to FHRP VIP misconfiguration requires comparing active device settings against baseline logical specifications.
2
Differentiate between logical and physical documentation types.
Physical diagrams and wiring schematics illustrate hardware placement, port assignments, and cabling pinouts, whereas logical diagrams illustrate protocol relationships, IP addressing, subnets, and virtual endpoints.
Virtual IPs (VIPs) exist at Layer 3 as logical constructs independent of physical cabling and rack positioning.
3
Select the authoritative documentation source.
The logical network topology diagram and IP address management (IPAM) baseline document provide the authoritative reference for VIP allocations and subnet mappings.
These documents contain explicit records of logical network constructs essential for validating default gateway settings across redundant topologies.

Key Concept

Logical Network Diagrams and IP Baseline Documentation
Question 83Question

A network technician needs to establish an encrypted command-line management session with a core switch across the local subnet. Which protocol should the technician use to ensure administrative credentials are encrypted during transmission?

Show answer & explanation

Answer: SSH

Answer

SSH (Secure Shell)
SSH provides a secure, encrypted transport layer for remote command-line interface (CLI) administration of network devices.

Step-by-Step Solution

1
Identify the operational requirement.
The requirement calls for interactive command-line access with encrypted network communications.
Managing network hardware via unencrypted sessions creates critical security vulnerabilities.
2
Evaluate remote access protocols against security criteria.
SSH provides encrypted shell sessions over TCP port 22, fulfilling the security requirement.
Protocols such as Telnet or HTTP transmit credentials in plaintext, whereas SSH uses cryptography to secure remote administration.

Key Concept

Secure Remote Access with SSH
Question 84Question

A network administrator configures an extended IPv4 Access Control List (ACL) on a router interface filtering inbound traffic toward an internal database subnet (10.50.10.0/2410.50.10.0/24). The ACL is designed to meet three requirements:
1. Allow secure administration from a jump host at 10.50.1.1510.50.1.15 via SSH (TCP 22).
2. Allow application servers on subnet 10.50.2.0/2410.50.2.0/24 to access the database server at 10.50.10.10010.50.10.100 on TCP port 5432.
3. Block all other traffic originating from subnet 10.50.2.0/2410.50.2.0/24.

The administrator enters the following ACL entries in sequential order:
- Entry 10: `permit tcp host 10.50.1.15 10.50.10.0 0.0.0.255 eq 22`
- Entry 20: `deny ip 10.50.2.0 0.0.0.255 10.50.10.0 0.0.0.255`
- Entry 30: `permit tcp 10.50.2.0 0.0.0.255 host 10.50.10.100 eq 5432`

During testing, application servers on subnet 10.50.2.0/2410.50.2.0/24 are unable to establish database connections to 10.50.10.100:543210.50.10.100:5432. Which of the following best explains why this configuration fails?

Show answer & explanation

Answer: The sequential top-down evaluation matches application server traffic against Entry 20 first, resulting in an explicit deny before Entry 30 is evaluated.

Answer

The configuration fails because ACL rules are evaluated sequentially from top to bottom, causing traffic from 10.50.2.0/24 to match the broad deny rule in Entry 20 before reaching the specific permit rule in Entry 30.
Router access control lists utilize a first-match rule processing mechanism. Because Entry 20 specifies a broad deny for all IP traffic from subnet 10.50.2.0/24 to 10.50.10.0/24, packets intended for port 5432 match Entry 20 immediately and are discarded. Entry 30 is never evaluated for this traffic. To resolve this, specific permit rules must always precede broader deny statements.

Step-by-Step Solution

1
Analyze how Access Control Lists evaluate incoming packets.
Network devices evaluate ACL entries sequentially starting from the lowest line number (top-down) and apply the action of the first matching rule, terminating further rule checks for that packet.
Understanding first-match execution logic is essential for placing ACL entries correctly.
2
Trace a packet sent from an application server (e.g., 10.50.2.50) to the database server (10.50.10.100:5432) through the ACL entries.
Entry 10 does not match (source host differs). Entry 20 matches because the source 10.50.2.50 is within 10.50.2.0/24 and destination 10.50.10.100 is within 10.50.10.0/24.
Determining which entry matches first identifies why the traffic is dropped.
3
Determine the necessary structural fix for the ACL sequence.
Entry 30 (the specific permit rule for port 5432) must be placed above Entry 20 (the broad deny rule for the subnet).
Specific permit rules must precede broader deny statements to prevent premature packet drops.

Key Concept

ACL Sequential Logic and Rule Ordering
Question 85Question

A network technician discovers that queries sent to the local DNS server for a company intranet portal are resolving to an unauthorized external IP address due to corrupted cache entries. Which network attack vector does this scenario describe?

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Answer: DNS poisoning

Answer

DNS poisoning
DNS poisoning directly targets the DNS caching mechanism by inserting invalid IP mappings into the resolver's store, forcing clients requesting domain lookups to connect to an attacker-controlled endpoint.

Step-by-Step Solution

1
Analyze the reported symptom in the scenario
Domain name resolution requests are being diverted to an unauthorized IP address because false entries were stored in the DNS server cache.
Identifying where the manipulation occurs (Layer 7 DNS cache vs Layer 2 ARP cache) is critical for determining the attack vector.
2
Match the mechanism to the correct attack classification
Injecting fraudulent IP mappings into a DNS caching resolver is defined as DNS cache poisoning.
This mechanism manipulates name resolution services to misdirect client connection requests.

Key Concept

DNS Cache Poisoning
Question 86Question

A security technician needs to configure an extended Access Control List (ACL) rule on a router to permit secure HTTPS web traffic from an internal subnet to an external web server. Which transport protocol and destination port combination must be specified in the ACL rule to correctly match this traffic?

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Answer: TCP protocol with destination port 443

Answer

TCP protocol with destination port 443
HTTPS (Hypertext Transfer Protocol Secure) encrypts web communications using TLS/SSL and operates over the reliable Transmission Control Protocol (TCP) on standard destination port 443. An extended Access Control List filtering this traffic must specify TCP as the protocol and 443 as the destination port.

Step-by-Step Solution

1
Identify the application layer protocol requested in the scenario.
The scenario specifies secure HTTPS web traffic.
Understanding the required application service determines the transport protocol and port number.
2
Determine the transport layer protocol used by HTTPS.
HTTPS requires TCP to establish reliable, stateful connections via TLS/SSL.
Web traffic requires reliable deliverability and packet ordering provided by TCP rather than connectionless UDP.
3
Determine the standard destination port assigned to HTTPS.
The standard well-known port for HTTPS is port 443.
Standard port numbers allow firewalls and extended ACLs to inspect and filter network traffic accurately based on service type.

Key Concept

ACL Port and Protocol Matching for Secure Web Services
Question 87Question

A network administrator is auditing the physical and environmental security controls of a newly built enterprise data center. During inspection, the administrator notes that the HVAC system is maintaining ambient relative humidity at 15% inside the server room. Which of the following recommendations should the administrator make to address the primary risk caused by this environmental condition?

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Answer: Increase relative humidity to between 40% and 55% to mitigate the heightened risk of electrostatic discharge (ESD).

Answer

Increase relative humidity to between 40% and 55% to mitigate the heightened risk of electrostatic discharge (ESD).
Low relative humidity (below 40%) causes air to become excessively dry, significantly increasing the accumulation of static electricity. This creates a severe risk of electrostatic discharge (ESD) events that can destroy delicate microprocessors and network expansion cards. Maintaining relative humidity between 40% and 55% safely dissipates static charges while avoiding condensation.

Step-by-Step Solution

1
Analyze the reported relative humidity level of 15% in the server room.
Identify that 15% humidity is extremely dry and falls well below the industry-standard minimum threshold of 40%.
Air with low moisture content acts as an insulator, allowing static electrical charges to accumulate easily on surfaces, cables, and personnel.
2
Determine the primary physical hardware threat associated with low humidity.
Recognize that static buildup leads to electrostatic discharge (ESD), which can permanently damage sensitive network switches, routers, and server motherboards.
ESD events can occur at voltage levels far below what a human can feel, causing immediate component destruction or latent degradation.
3
Select the appropriate environmental control adjustment.
Recommend increasing relative humidity to the standard target range of 40% to 55%.
This target range prevents static electricity accumulation while remaining low enough to prevent moisture condensation on hardware surfaces.

Key Concept

Environmental Controls and Humidity Management in Server Rooms
Question 88Question

A network operations team is upgrading the enterprise monitoring architecture to address bandwidth degradation, security compliance, and service level agreement (SLA) tracking across site-to-site WAN links. Match each network performance monitoring technology or protocol on the left with the specific operational monitoring requirement it directly satisfies on the right.

Click a left item, then click its matching right item

Items

NetFlow / IPFIX Flow Record Telemetry
SNMPv3 with authPriv Security Level
IP SLA Active Synthetic Probing
Full Packet Capture via Physical Network TAP

Matches

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Answer

NetFlow / IPFIX matches with quantifying top talkers and protocol breakdown without payload storage; SNMPv3 authPriv matches with securely polling system health metrics over encrypted connections; IP SLA active probing matches with measuring latency, jitter, and loss for VoIP SLAs; Full Packet Capture matches with inspecting exact bit-level TCP behavior and raw payload contents.
Each technology satisfies a distinct performance monitoring requirement: NetFlow/IPFIX aggregates layer 3/4 header stats for top talkers without storing payloads; SNMPv3 authPriv enforces encryption and authentication for device health polling; IP SLA injects synthetic probes to calculate delay, jitter, and loss for voice SLAs; and full packet capture duplicates physical traffic for low-level TCP and payload analysis.

Step-by-Step Solution

1
Analyze the primary telemetry mechanism of each monitoring solution.
Differentiated flow metadata (NetFlow/IPFIX), pull-based device state management (SNMPv3), synthetic probe traffic (IP SLA), and line-rate frame mirroring (TAP/PCAP).
Each monitoring methodology addresses a distinct diagnostic requirement within network operations.
2
Align each operational scenario requirement with the capability of the matching telemetry tool.
Matched SNMPv3 authPriv to encrypted MIB polling, NetFlow to payload-less flow summaries, IP SLA to active voice path metrics, and PCAP to deep payload and frame analysis.
Correctly pairs telemetry data collection capabilities with performance enterprise objectives.

Key Concept

Network Performance Telemetry Methods and Metric Collection
Question 89Question

A network engineer at a high-density regional hospital is upgrading the facility's wireless infrastructure to improve security and auditability. The security policy mandates that every medical staff member must authenticate to the corporate SSID using their unique Active Directory credentials, allowing central logging of user sessions via 802.1X RADIUS. During the deployment planning, a technician proposes configuring WPA3-Personal with Simultaneous Authentication of Equals (SAE) and distributing unique static passphrases to staff groups to avoid modifying existing RADIUS server certificate policies. Which of the following best explains why the technician's proposed solution fails to meet the corporate security mandate, and what configuration must be enforced instead?

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Answer: WPA3-Personal using SAE relies on pre-shared passphrase authentication rather than centralized 802.1X RADIUS credential validation; WPA3-Enterprise must be deployed to integrate with Active Directory user identities.

Answer

WPA3-Personal using SAE relies on pre-shared passphrase authentication rather than centralized 802.1X RADIUS credential validation; WPA3-Enterprise must be deployed to integrate with Active Directory user identities.
WPA3-Personal uses Simultaneous Authentication of Equals (SAE) to secure password-based connections against offline dictionary attacks, but it remains a pre-shared key technology that cannot pass individual user credentials to an 802.1X RADIUS server. To fulfill the mandate of authenticating staff members individually against Active Directory with centralized RADIUS accounting, the network must enforce WPA3-Enterprise.

Step-by-Step Solution

1
Analyze the security mandate requirements
Identified two primary requirements: individual user credential authentication against Active Directory via 802.1X RADIUS and centralized session auditability.
Security mandates require mapping network access to unique user identities rather than shared group credentials.
2
Evaluate the technician's proposed WPA3-Personal (SAE) solution
Determined that SAE (Simultaneous Authentication of Equals) replaces the WPA2-Pre-Shared Key (PSK) mechanism to protect against offline dictionary attacks, but still operates on a passphrase basis.
SAE lacks support for Extensible Authentication Protocol (EAP) mechanisms needed to query backend 802.1X RADIUS servers for individual domain credentials.
3
Determine the required security standard
Selected WPA3-Enterprise as the mandatory standard.
WPA3-Enterprise explicitly enforces 802.1X EAP authentication, enabling individual Active Directory user authentication and RADIUS session accounting.

Key Concept

Wireless Security Standards and Encryption Protocols
Question 90Question

A network administrator is configuring an extended IPv4 Access Control List (ACL) on a router interface to control traffic from the client workstation subnet (172.16.10.0/24172.16.10.0/24) targeting the corporate server farm subnet (10.5.0.0/2410.5.0.0/24). The security policy specifies the following requirements for traffic destined for the database server (10.5.0.2010.5.0.20) and the rest of the server farm:

1. SSH administrative access (TCP port 22) to host 10.5.0.2010.5.0.20 must be permitted ONLY from the primary administrator workstation at IP address 172.16.10.5172.16.10.5.
2. All other SSH traffic (TCP port 22) to host 10.5.0.2010.5.0.20 originating from subnet 172.16.10.0/24172.16.10.0/24 must be explicitly blocked.
3. All non-SSH TCP traffic from subnet 172.16.10.0/24172.16.10.0/24 to host 10.5.0.2010.5.0.20 must be permitted.
4. Non-TCP IP traffic from subnet 172.16.10.0/24172.16.10.0/24 to host 10.5.0.2010.5.0.20 must be blocked.
5. All IP traffic from subnet 172.16.10.0/24172.16.10.0/24 to all other servers in subnet 10.5.0.0/2410.5.0.0/24 must be permitted.

In what top-to-bottom sequential order must the ACL entries be placed on the interface to enforce this security policy without rule shadowing?

Drag items to arrange them in the correct order

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Answer

The correct sequence from top to bottom is: permit SSH for host 172.16.10.5 -> deny SSH for subnet 172.16.10.0/24 -> permit all TCP for subnet 172.16.10.0/24 to host 10.5.0.20 -> deny all IP for subnet 172.16.10.0/24 to host 10.5.0.20 -> permit all IP for subnet 172.16.10.0/24 to subnet 10.5.0.0/24.
Extended Access Control Lists evaluate entries sequentially from top to bottom, stopping at the first match. To enforce granular control without rule shadowing, rules must be ordered from most specific to least specific: (1) Host-specific SSH permit for host 172.16.10.5, (2) Subnet-wide SSH deny for host 10.5.0.20, (3) Subnet-wide TCP permit for host 10.5.0.20, (4) Subnet-wide IP deny for host 10.5.0.20, and (5) Subnet-wide IP permit for the entire 10.5.0.0/24 destination network.

Step-by-Step Solution

1
Place the specific host SSH permit statement first.
access-list 102 permit tcp host 172.16.10.5 host 10.5.0.20 eq 22 is evaluated first.
ACLs process rules sequentially top-to-bottom. Placing host 172.16.10.5 first allows the administrator's workstation to connect over SSH before any broader deny rules take effect.
2
Place the subnet SSH deny statement second.
access-list 102 deny tcp 172.16.10.0 0.0.0.255 host 10.5.0.20 eq 22 is evaluated second.
Placing this rule immediately below the host SSH permit entry blocks SSH access for all other hosts in subnet 172.16.10.0/24 while preventing it from shadowing the permit entry above.
3
Place the general TCP permit statement for host 10.5.0.20 third.
access-list 102 permit tcp 172.16.10.0 0.0.0.255 host 10.5.0.20 is evaluated third.
Because SSH (port 22) has already been filtered by the top two rules, this rule permits all other TCP traffic (e.g., HTTP/HTTPS) to host 10.5.0.20. If placed above rule 2, it would incorrectly permit SSH for the entire subnet.
4
Place the full IP deny statement for host 10.5.0.20 fourth.
access-list 102 deny ip 172.16.10.0 0.0.0.255 host 10.5.0.20 is evaluated fourth.
This blocks all non-TCP IP traffic (such as ICMP or UDP) targeting host 10.5.0.20. Placing it below the TCP permit rule ensures TCP traffic to host 10.5.0.20 is allowed first.
5
Place the subnet-wide IP permit statement fifth.
access-list 102 permit ip 172.16.10.0 0.0.0.255 10.5.0.0 0.0.0.255 is evaluated fifth.
This allows traffic to all other servers in subnet 10.5.0.0/24. Placing it at the bottom prevents it from permitting unauthorized traffic to host 10.5.0.20.

Key Concept

ACL Rule Evaluation Order and Shadowing Prevention
Question 91Question

A network administrator is designing security controls for transmitting sensitive corporate financial records between two remote office sites over an untrusted public network. The controls must ensure that unauthorized parties cannot intercept and read the data, and that any tampering during transit is immediately detected. Which TWO of the following technical mechanisms should the administrator implement to satisfy these requirements? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: Encapsulating Security Payload (ESP) encryption to enforce data confidentiality; Hash-based Message Authentication Codes (HMAC) to guarantee data integrity

Answer

Encapsulating Security Payload (ESP) encryption and Hash-based Message Authentication Codes (HMAC) are the correct mechanisms.
Encapsulating Security Payload (ESP) encryption ensures that data payload contents cannot be read by unauthorized interceptors (Confidentiality). Hash-based Message Authentication Codes (HMAC) ensure that any changes made to the data during transit can be detected by verifying the cryptographic hash (Integrity). Together, these mechanisms satisfy both mandatory requirements.

Step-by-Step Solution

1
Identify the confidentiality requirement
Preventing unauthorized interception and reading of data in transit requires payload encryption.
Encryption transforms plaintext into ciphertext so unauthenticated listeners cannot decode the content.
2
Identify the integrity requirement
Detecting unauthorized tampering or modification of data in transit requires cryptographic hashing or message authentication codes.
Integrity mechanisms allow the recipient to verify that packet contents have not altered since transmission.
3
Select matching technical controls
ESP encryption delivers confidentiality, and HMAC delivers data integrity.
These controls directly map to the confidentiality and integrity pillars of the CIA triad.

Key Concept

CIA Triad: Confidentiality and Integrity Controls in Transit
Question 92Question

A network security engineer is deploying a remote access VPN solution using L2TP over IPsec (L2TP/IPsec) to support remote workers connecting from behind residential NAT routers. Authentication will be offloaded to a central enterprise AAA server. Which of the following port and protocol configurations must be permitted on the network firewalls and VPN gateway to ensure successful connection establishment and authentication? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: UDP ports 500 and 4500 must be opened inbound to allow Internet Key Exchange (IKE) negotiation and IPsec NAT Traversal (NAT-T).; UDP port 1701 must be permitted to transport encapsulated Layer 2 Tunneling Protocol data frames.

Answer

The correct configurations are opening UDP ports 500 and 4500 for IKE negotiation and IPsec NAT-T, and permitting UDP port 1701 for L2TP frame encapsulation.
In an L2TP/IPsec VPN deployment across NAT gateways, IPsec requires UDP port 500 for initial IKE negotiations and UDP port 4500 for NAT Traversal (NAT-T), which wraps encrypted ESP packets inside UDP headers to preserve integrity across PAT devices. Meanwhile, L2TP handles session encapsulation using UDP port 1701.

Step-by-Step Solution

1
Identify the key requirements for L2TP over IPsec tunnel establishment behind NAT.
IPsec relies on IKE (UDP port 500) for security association negotiation. Because NAT alters IP headers and breaks IPsec ESP integrity checks, NAT Traversal (NAT-T) encapsulates ESP within UDP port 4500 packets.
NAT-T allows IPsec traffic to traverse Network Address Translation (PAT) devices smoothly.
2
Determine the transport protocol and port used by L2TP.
L2TP handles multiplexing and PPP frame encapsulation over UDP port 1701.
L2TP does not use TCP; it uses UDP for low-overhead encapsulation before IPsec secures the packet payload.
3
Differentiate AAA protocol behaviors for remote user authentication.
RADIUS uses UDP ports 1812/1813 (or legacy 1645/1646) and encrypts only passwords, while TACACS+ uses TCP port 49 and encrypts the entire payload.
Confusing RADIUS and TACACS+ port assignments and encryption scope leads to incorrect firewall rules for backend AAA traffic.

Key Concept

L2TP/IPsec VPN NAT Traversal and AAA Protocol Integration
Question 93Question

During a high-availability failover test on an enterprise subnet, client workstations lose all outbound network connectivity whenever the primary active router is powered off. Network logs confirm that the secondary router successfully assumes the active role within the First Hop Redundancy Protocol (FHRP) group and advertises the virtual MAC address. However, workstations fail to route traffic to external networks until the primary router is brought back online. Which of the following is the primary cause of this connectivity loss?

Show answer & explanation

Answer: Workstations were configured with the physical interface IP address of the primary router as their default gateway instead of the FHRP Virtual IP (VIP).

Answer

Workstations were configured with the physical interface IP address of the primary router as their default gateway instead of the FHRP Virtual IP (VIP).
For First Hop Redundancy Protocols (FHRP) like HSRP or VRRP to provide seamless gateway failover, all network endpoints must use the Virtual IP (VIP) as their configured default gateway. If clients are statically or dynamically assigned the physical interface IP of the active router, traffic will continue flowing exclusively to that physical device. When that hardware fails, client traffic drops despite the standby router taking over the FHRP group and virtual MAC address.

Step-by-Step Solution

1
Analyze FHRP operation and failover mechanics
FHRP protocols (such as HSRP or VRRP) group multiple physical routers into a single logical gateway sharing a Virtual IP (VIP) and Virtual MAC address.
For high availability to function seamlessly, end host devices must send default gateway traffic to the VIP rather than individual physical interface IPs.
2
Evaluate the observed failure symptom against host configurations
The secondary router successfully transitioned to active status and answered for the virtual MAC, but workstations remained unable to reach external networks.
This behavior indicates that workstation traffic was targeted directly to the primary router's physical IP address, bypassing the virtual gateway entirely.
3
Identify the misconfiguration cause
The static or DHCP-assigned default gateway setting on workstations was pointing to the primary physical IP (e.g., 10.0.1.2) instead of the virtual IP (e.g., 10.0.1.1).
When the primary router went down, the workstations had no mechanism to dynamically route traffic to the standby router's physical IP.

Key Concept

First Hop Redundancy Protocol Virtual IP Configuration
Estimated Time:1m 30s
Question 94Question

An organization is deploying an enterprise remote access VPN solution for mobile users who frequently operate behind Carrier-Grade NAT (CGNAT) and restrictive corporate firewalls. The network security team requires mutual certificate authentication, complete confidentiality of internal IP headers, and seamless NAT traversal without dropping integrity checks. Which of the following technical configurations and protocol mechanisms must be selected to satisfy these requirements? (Select TWO.)

Select all that apply

Show answer & explanation

Answer: Enable IPsec NAT-Traversal (NAT-T) to encapsulate Encapsulating Security Payload (ESP) packets within UDP port 4500 when an intermediate NAT device is detected.; Utilize IPsec Encapsulating Security Payload (ESP) in Tunnel mode paired with EAP-TLS to encrypt the entire inner IP packet and enforce mutual certificate authentication.

Answer

The required configurations are enabling NAT-Traversal to encapsulate ESP packets in UDP port 4500 and deploying IPsec ESP in Tunnel mode combined with EAP-TLS for full IP packet encryption and mutual certificate authentication.
The correct selection involves leveraging NAT-Traversal (NAT-T) over UDP port 4500 and deploying ESP in Tunnel mode with EAP-TLS. ESP Tunnel mode encrypts both the inner payload and the inner IP header, fulfilling the requirement for complete packet confidentiality, while EAP-TLS ensures mutual certificate authentication. NAT-T wraps ESP traffic inside standard UDP packets so stateful firewalls and CGNAT devices can properly map translation entries without invalidating cryptographic checksums.

Step-by-Step Solution

1
Analyze confidentiality and authentication requirements
Full confidentiality of the original IP header and payload requires IPsec ESP in Tunnel mode. Mutual certificate authentication is provided by EAP-TLS.
Transport mode leaves the original IP header unencrypted, while Tunnel mode encapsulates the complete original IP packet inside a new IP header.
2
Evaluate NAT traversal compatibility
Standard ESP operates directly on top of IP (IP Protocol 50) without L4 port numbers, causing NAT mapping failures. NAT-T encapsulates ESP in UDP port 4500 after detecting NAT during IKE negotiations.
Encapsulating ESP in UDP port 4500 enables intermediate routers and CGNAT gateways to track network translation tables via standard port numbers.
3
Evaluate protocol flaws in incorrect choices
Authentication Header (AH) does not offer encryption and fails across NAT. Additionally, IKEv2 relies on UDP port 500/4500, not TCP port 500.
AH includes the IP header in its ICV calculation, making it incompatible with NAT IP address translation, while TCP port 500 is a non-existent standard port combination for IKE.

Key Concept

IPsec Tunnel Mode vs. Transport Mode & NAT-Traversal Mechanisms
Question 95Question

A network administrator needs to construct an IPv4 extended Access Control List (ACL) to filter traffic originating from the internal subnet 192.168.1.0/24192.168.1.0/24. The security policy requires the following requirements in order of processing:
1. Allow host 192.168.1.25192.168.1.25 to access web server 10.10.10.510.10.10.5 using secure HTTPS (port 443).
2. Block all other hosts on the 192.168.1.0/24192.168.1.0/24 subnet from reaching server 10.10.10.510.10.10.5.
3. Permit all remaining outbound traffic from subnet 192.168.1.0/24192.168.1.0/24 to any other destination.
4. Catch and drop all remaining unspecified IP traffic.

In what order should these ACL statements be evaluated from top to bottom to satisfy the security policy without shadowing any rules?

Drag items to arrange them in the correct order

Show answer & explanation

Answer

The correct order of ACL statements from top to bottom is: (1) permit tcp host 192.168.1.25 host 10.10.10.5 eq 443, (2) deny ip 192.168.1.0 0.0.0.255 host 10.10.10.5, (3) permit ip 192.168.1.0 0.0.0.255 any, and (4) deny ip any any.
Router Access Control Lists process entries sequentially from top to bottom and stop at the first matching rule. To ensure correct policy enforcement, rules must be arranged from most specific (individual host and port permissions) to most general (subnet permits and implicit deny statements). Placing the host-specific permit for TCP port 443 first allows host 192.168.1.25 to reach server 10.10.10.5. Placing the subnet deny rule second blocks all other hosts in 192.168.1.0/24 from reaching server 10.10.10.5. Placing the subnet permit rule third allows subnet 192.168.1.0/24 to reach all other destinations. Placing the deny-all rule last catches all non-matching traffic.

Step-by-Step Solution

1
Place the most specific host exception rule at the top of the list.
traffic matching host 192.168.1.25 destined for 10.10.10.5 on TCP port 443 is matched immediately and permitted.
ACLs process rules sequentially using a first-match mechanism. Host-specific rules must precede subnet-level rules to avoid being shadowed.
2
Place the specific subnet-to-server deny rule immediately after the host permit exception.
Any other packet originating from 192.168.1.0/24 heading to 10.10.10.5 is matched and denied.
This enforces the requirement to block the rest of the 192.168.1.0/24 subnet from reaching the server.
3
Place the general permit rule for subnet 192.168.1.0/24 after the server restriction.
Traffic from 192.168.1.0/24 aimed at destinations other than 10.10.10.5 is permitted.
Packets reaching this rule have already been checked against the server restriction rules, allowing normal outgoing network communication for the subnet.
4
Place the default deny statement at the bottom of the ACL.
Any packet not matching the 192.168.1.0/24 source criteria is explicitly dropped.
Ensures zero-trust security by dropping all unhandled packets at the end of the ACL processing sequence.

Key Concept

First-match sequential rule evaluation and rule shadowing prevention in Access Control Lists (ACLs)
Estimated Time:1m 0s
Question 96Question

A network engineer is configuring a centralized AAA server to support 802.1X port-based network access control across an enterprise wireless deployment. Which configuration parameters accurately specify the default transport protocol and port assignments required for standard RADIUS authentication and accounting services?

Show answer & explanation

Answer: UDP ports 1812 for authentication and 1813 for accounting

Answer

The standard configuration for RADIUS authentication and accounting uses UDP ports 1812 and 1813, respectively.
Standard RADIUS implementation relies on UDP transport, utilizing port 1812 for authentication/authorization and port 1813 for accounting.

Step-by-Step Solution

1
Identify the transport protocol used by RADIUS
RADIUS uses User Datagram Protocol (UDP) for low-overhead client-server communication.
Understanding transport protocol requirements is critical for proper firewall and service configuration.
2
Identify standard RADIUS service port assignments
RFC 2865 assigns UDP port 1812 for RADIUS authentication/authorization, and RFC 2866 assigns UDP port 1813 for RADIUS accounting.
Centralized AAA authentication servers rely on these specific port bindings to separate authentication requests from audit/accounting logs.

Key Concept

RADIUS Operational Parameters and Port Assignments
Question 97Question

A system auditor observes that malicious encrypted TLS command-and-control (C2) traffic traversing an internal server VLAN went completely undetected by a newly installed Network Intrusion Detection System (NIDS) connected to a core switch SPAN port. The organization requires a security solution that can inspect host system calls, file integrity changes, and decrypted application memory buffers on critical servers without altering network physical cabling or introducing a single point of failure that causes latency on the switch hardware. Which solution should be implemented to fulfill these security and architectural requirements?

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Answer: Deploy a Host-based Intrusion Detection System (HIDS) directly on the critical target servers.

Answer

Deploying a Host-based Intrusion Detection System (HIDS) directly on the critical target servers provides local process, file integrity, and decrypted memory visibility without impacting network switch latency or introducing single-point-of-failure hardware topology dependencies.
Deploying a Host-based Intrusion Detection System (HIDS) directly on the target servers allows inspection of host system calls, unencrypted memory buffers, system logs, and file modifications. Because HIDS operates on the endpoint OS rather than inline on the physical network switch, it avoids introducing network latency or inline failure points while solving the network encryption visibility gap.

Step-by-Step Solution

1
Analyze the limitation of out-of-band network-level monitoring (NIDS) against encrypted traffic.
Network-based passive sensors (NIDS) connected to SPAN/TAP ports only inspect network packet payloads in transit, which remain encrypted under TLS/SSL.
Out-of-band NIDS cannot inspect payload content or host memory without TLS session keys or host-level access.
2
Evaluate host-level versus network-level deployment options against constraints.
Host-based Intrusion Detection Systems (HIDS) monitor operating system calls, host log files, process activity, and unencrypted memory buffers locally on the host.
HIDS bypasses network transport encryption limitations by operating at the OS level while remaining out of the physical network forwarding path.
3
Select the host security solution that meets performance and reliability requirements.
Installing a HIDS on the target servers provides the necessary threat detection without adding physical latency or inline hardware network failure risks to switch links.
It fulfills the requirement for deep payload and host-state inspection without introducing inline network bottlenecks.

Key Concept

HIDS vs NIDS/NIPS Visibility and Deployment Architecture
Question 98Question

Following an emergency vendor security advisory regarding a remote code execution vulnerability in core routing hardware, an administrator is tasked with updating the operating system software. To minimize operational risk and strictly follow standardized patch management lifecycle procedures, which action should the administrator execute first prior to deploying the software update in the live environment?

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Answer: Validate and deploy the patch package within an isolated staging environment that mimics production configuration.

Answer

Validate and deploy the patch package within an isolated staging environment that mimics production configuration.
In enterprise patch management, safety and continuity mandate that patches and software maintenance packages are thoroughly evaluated in an isolated staging lab before hitting production. This process uncovers bug regressions, validates vendor claims, and confirms that recovery/rollback steps function properly.

Step-by-Step Solution

1
Analyze the patch deployment request and operational requirements
Identified the need to apply an emergency software update to critical core routers without causing unintended outages.
Production systems require risk mitigation before introducing code updates.
2
Evaluate standard patch management lifecycle phases
Determined that testing and validation in a staging/lab environment must precede production deployment.
Staging allows engineers to observe software behavior, verify dependencies, and confirm rollback steps safely.
3
Select the correct procedural starting point
Staging environment validation is selected as the primary mandatory action.
Direct production deployment or improper backup procedures increase failure risk significantly.

Key Concept

Structured Patch Management Lifecycle and Staging Environment Validation
Estimated Time:2m 0s
Question 99Question

A network administrator is configuring three adjacent 2.4 GHz wireless access points in an office floor plan. Which combination of channels should be assigned to these access points to prevent co-channel and adjacent-channel interference?

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Answer: Channels 1, 6, and 11

Answer

Channels 1, 6, and 11
Channels 1, 6, and 11 are the standard non-overlapping 20 MHz channels in the 2.4 GHz Wi-Fi spectrum. Assigning these distinct channels to adjacent access points prevents signal degradation caused by channel overlap.

Step-by-Step Solution

1
Identify the frequency band and channel separation requirements for 2.4 GHz Wi-Fi.
Standard 2.4 GHz 802.11 channels require 20 MHz of bandwidth, but center frequencies are spaced only 5 MHz apart.
To avoid frequency overlap, channels must have center frequencies spaced at least 20 MHz (4 channel intervals) apart.
2
Determine the non-overlapping channel set.
Selecting channels 1, 6, and 11 provides the necessary 25 MHz separation between channel center frequencies.
Channels 1, 6, and 11 allow multiple adjacent access points to operate without interfering with one another.

Key Concept

2.4 GHz Non-Overlapping Channel Assignment
Estimated Time:45s
Question 100Question

A network engineer is investigating intermittent packet loss and database session drops across a newly provisioned IPsec VPN tunnel between two enterprise data centers. After analyzing interface counters and running test ping sweeps with custom payload sizes, the engineer successfully proves that an MTU mismatch is causing packet fragmentation errors and confirms that lowering the tunnel interface MTU in a staging sandbox completely eliminates the drop count. According to the CompTIA troubleshooting methodology, which action should the engineer perform NEXT?

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Answer: Formulate a formal plan of action to modify the production MTU settings while identifying any potential side effects or service disruptions.

Answer

Formulate a formal plan of action to modify the production MTU settings while identifying any potential side effects or service disruptions.
The scenario indicates that Step 3 of the CompTIA troubleshooting methodology (Test the theory to determine cause) has just been successfully completed. According to the official methodology, the immediate next action is Step 4: Establish a plan of action to resolve the problem and identify potential effects, followed by implementing the solution. Planning out the deployment in production ensures changes do not cause unintended outages.

Step-by-Step Solution

1
Determine current step in the troubleshooting process.
The scenario describes a technician who tested a hypothesis in a lab setting and confirmed the root cause (MTU mismatch). This completes Step 3 (Test the theory to determine cause).
CompTIA methodology relies on a strict sequential workflow.
2
Identify the mandatory next step in the CompTIA 6-step process.
Step 4 is 'Establish a plan of action to resolve the problem and identify potential effects; implement the solution or escalate as necessary.'
Before making production changes, a technician must plan the deployment and evaluate potential downtime or collateral impact.
3
Evaluate the choices against Step 4.
The option advocating the formulation of a plan of action and assessment of side effects directly matches Step 4.
Other options jump ahead to Step 5 (verification), Step 6 (documentation), or regress to Step 1 (identification).

Key Concept

CompTIA Troubleshooting Methodology Step Sequence
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