CNT EXAM PRACTICE | STUDY GUIDE | COMPREHENSIVE TESTBANK WITH PRACTICE
QUESTIONS & ANSWERS | LATEST UPDATE 2026/2027 | ADVANCED REVIEW
TABLE OF CONTENTS
i. Network Architecture, Topologies, and Design
ii. OSI/TCP-IP Models and Protocol Analysis
iii. Ethernet, Switching, and VLANs
iv. IPv4/IPv6 Addressing and Subnetting
v. Routing, NAT, and Network Services
vi. Wireless Networking and Security
vii. Network Troubleshooting and Performance Analysis
viii. Infrastructure, Cabling, and Physical Layer
ix. Network Security, Reliability, and Best Practices
x. Documentation, Monitoring, and Professional Decision-Making
INTRODUCTION
This CNT practice examination is designed as an advanced review of core networking
competencies expected from professional network technicians and certification
candidates. The questions emphasize practical network architecture, Ethernet switching,
IP addressing, routing, wireless technologies, security, troubleshooting, cabling, and
network services. Rather than relying primarily on memorization, the examination
requires interpretation of technical symptoms, application of networking principles,
analysis of configurations, and selection of the most appropriate professional response.
Candidates should expect realistic scenarios involving performance degradation,
connectivity failures, segmentation, addressing, security controls, and infrastructure
decisions. The difficulty ranges from advanced to extremely challenging, making the set
useful for structured preparation, diagnostic practice, and higher-level certification
review.
Question 1
A technician is troubleshooting intermittent connectivity between two devices
connected to the same Ethernet switch. Both interfaces report link-up status, but the
switch's interface statistics show rapidly increasing CRC errors on one port. Which
action should the technician perform FIRST?
,A. Replace the switch's default gateway
B. Replace or test the physical cable and connectors
C. Reconfigure the remote device's DNS server
D. Disable spanning tree on the switch
🔴 Correct Answer: B. Replace or test the physical cable and connectors.
🔵 Explanation: CRC errors are normally associated with corrupted Ethernet frames and
commonly indicate a physical-layer problem such as damaged cabling, poor termination,
electromagnetic interference, or a failing interface. The physical medium should therefore
be investigated before making higher-layer configuration changes.
Question 2
An organization has 172.16.40.0/24 and needs to create subnets supporting at least 30
usable host addresses each while minimizing address waste. Which subnet mask
provides the appropriate solution?
A. /26
B. /27
C. /28
D. /29
🔴 Correct Answer: B. /27.
🔵 Explanation: A /27 subnet contains 32 total addresses, of which 30 are normally
usable for hosts after excluding the network and broadcast addresses. A /28 provides only
14 usable addresses, while /26 provides 62 and therefore wastes more addresses than
necessary.
Question 3
A workstation can successfully ping its default gateway and can reach internal servers
by IP address, but users cannot access those servers by hostname. Internet connectivity
by IP address also works. Which component should be investigated first?
A. DHCP relay agent
B. DNS resolution
C. Ethernet duplex configuration
D. Default gateway routing
🔴 Correct Answer: B. DNS resolution.
🔵 Explanation: Successful communication using IP addresses demonstrates that basic
,Layer 2 and Layer 3 connectivity is functioning. Failure specifically when hostnames are
used strongly indicates a DNS configuration, resolution, or availability problem.
Question 4
A network administrator needs to separate Finance, Human Resources, and Engineering
traffic while allowing controlled communication between the departments. All three
groups use the same physical switching infrastructure. Which solution is MOST
appropriate?
A. Implement separate VLANs with inter-VLAN routing
B. Assign all departments to the same VLAN and use different DNS suffixes
C. Configure separate default gateways without VLANs
D. Increase the Ethernet MTU for each department
🔴 Correct Answer: A. Implement separate VLANs with inter-VLAN routing.
🔵 Explanation: VLANs provide logical Layer 2 segmentation on shared switching
infrastructure. Inter-VLAN routing then permits controlled Layer 3 communication
between those segments while allowing security policies and access controls to be
applied.
Question 5
A switch receives a frame whose destination MAC address is not present in its MAC
address table. What should the switch normally do if the destination is not the same
port on which the frame arrived?
A. Drop the frame immediately
B. Send the frame only to the default gateway
C. Flood the frame out appropriate ports within the same VLAN
D. Convert the frame into an IP packet
🔴 Correct Answer: C. Flood the frame out appropriate ports within the same VLAN.
🔵 Explanation: An unknown unicast destination is normally flooded within the relevant
VLAN, excluding the ingress port. Once the destination device responds, the switch can
learn its MAC address and subsequently forward frames specifically.
Question 6
A company receives the IPv4 network 192.168.100.0/24 and requires four equal-sized
subnets. Which subnetting approach is appropriate?
, A. Borrow 1 host bit and use /25
B. Borrow 2 host bits and use /26
C. Borrow 3 host bits and use /27
D. Borrow 4 host bits and use /28
🔴 Correct Answer: B. Borrow 2 host bits and use /26.
🔵 Explanation: Creating four equal subnets requires 2 borrowed bits because 2² = 4.
Increasing the prefix from /24 to /26 produces four /26 subnets, each containing 64 total
addresses and 62 normally usable host addresses.
Question 7
A technician observes that users on a switch experience severe performance
degradation only during periods of heavy broadcast activity. Unicast traffic remains
comparatively stable. Which design change would BEST address the underlying
problem?
A. Increase DNS TTL values
B. Create appropriate VLAN boundaries to reduce broadcast domains
C. Disable MAC address learning
D. Replace IPv4 with static addressing
🔴 Correct Answer: B. Create appropriate VLAN boundaries to reduce broadcast
domains.
🔵 Explanation: Broadcast traffic is contained within a Layer 2 broadcast domain. Proper
VLAN segmentation reduces the number of devices receiving broadcasts and can
substantially limit the propagation of excessive broadcast traffic.
Question 8
A network uses DHCP. After a DHCP server becomes unavailable, newly connected
clients cannot obtain addresses, but existing clients continue functioning temporarily.
Which explanation BEST accounts for this behavior?
A. Existing leases may remain valid until their lease periods expire
B. DHCP automatically converts every client to IPv6
C. Switches permanently cache DHCP leases for all clients
D. DNS automatically assigns replacement IPv4 addresses
🔴 Correct Answer: A. Existing leases may remain valid until their lease periods
expire.
QUESTIONS & ANSWERS | LATEST UPDATE 2026/2027 | ADVANCED REVIEW
TABLE OF CONTENTS
i. Network Architecture, Topologies, and Design
ii. OSI/TCP-IP Models and Protocol Analysis
iii. Ethernet, Switching, and VLANs
iv. IPv4/IPv6 Addressing and Subnetting
v. Routing, NAT, and Network Services
vi. Wireless Networking and Security
vii. Network Troubleshooting and Performance Analysis
viii. Infrastructure, Cabling, and Physical Layer
ix. Network Security, Reliability, and Best Practices
x. Documentation, Monitoring, and Professional Decision-Making
INTRODUCTION
This CNT practice examination is designed as an advanced review of core networking
competencies expected from professional network technicians and certification
candidates. The questions emphasize practical network architecture, Ethernet switching,
IP addressing, routing, wireless technologies, security, troubleshooting, cabling, and
network services. Rather than relying primarily on memorization, the examination
requires interpretation of technical symptoms, application of networking principles,
analysis of configurations, and selection of the most appropriate professional response.
Candidates should expect realistic scenarios involving performance degradation,
connectivity failures, segmentation, addressing, security controls, and infrastructure
decisions. The difficulty ranges from advanced to extremely challenging, making the set
useful for structured preparation, diagnostic practice, and higher-level certification
review.
Question 1
A technician is troubleshooting intermittent connectivity between two devices
connected to the same Ethernet switch. Both interfaces report link-up status, but the
switch's interface statistics show rapidly increasing CRC errors on one port. Which
action should the technician perform FIRST?
,A. Replace the switch's default gateway
B. Replace or test the physical cable and connectors
C. Reconfigure the remote device's DNS server
D. Disable spanning tree on the switch
🔴 Correct Answer: B. Replace or test the physical cable and connectors.
🔵 Explanation: CRC errors are normally associated with corrupted Ethernet frames and
commonly indicate a physical-layer problem such as damaged cabling, poor termination,
electromagnetic interference, or a failing interface. The physical medium should therefore
be investigated before making higher-layer configuration changes.
Question 2
An organization has 172.16.40.0/24 and needs to create subnets supporting at least 30
usable host addresses each while minimizing address waste. Which subnet mask
provides the appropriate solution?
A. /26
B. /27
C. /28
D. /29
🔴 Correct Answer: B. /27.
🔵 Explanation: A /27 subnet contains 32 total addresses, of which 30 are normally
usable for hosts after excluding the network and broadcast addresses. A /28 provides only
14 usable addresses, while /26 provides 62 and therefore wastes more addresses than
necessary.
Question 3
A workstation can successfully ping its default gateway and can reach internal servers
by IP address, but users cannot access those servers by hostname. Internet connectivity
by IP address also works. Which component should be investigated first?
A. DHCP relay agent
B. DNS resolution
C. Ethernet duplex configuration
D. Default gateway routing
🔴 Correct Answer: B. DNS resolution.
🔵 Explanation: Successful communication using IP addresses demonstrates that basic
,Layer 2 and Layer 3 connectivity is functioning. Failure specifically when hostnames are
used strongly indicates a DNS configuration, resolution, or availability problem.
Question 4
A network administrator needs to separate Finance, Human Resources, and Engineering
traffic while allowing controlled communication between the departments. All three
groups use the same physical switching infrastructure. Which solution is MOST
appropriate?
A. Implement separate VLANs with inter-VLAN routing
B. Assign all departments to the same VLAN and use different DNS suffixes
C. Configure separate default gateways without VLANs
D. Increase the Ethernet MTU for each department
🔴 Correct Answer: A. Implement separate VLANs with inter-VLAN routing.
🔵 Explanation: VLANs provide logical Layer 2 segmentation on shared switching
infrastructure. Inter-VLAN routing then permits controlled Layer 3 communication
between those segments while allowing security policies and access controls to be
applied.
Question 5
A switch receives a frame whose destination MAC address is not present in its MAC
address table. What should the switch normally do if the destination is not the same
port on which the frame arrived?
A. Drop the frame immediately
B. Send the frame only to the default gateway
C. Flood the frame out appropriate ports within the same VLAN
D. Convert the frame into an IP packet
🔴 Correct Answer: C. Flood the frame out appropriate ports within the same VLAN.
🔵 Explanation: An unknown unicast destination is normally flooded within the relevant
VLAN, excluding the ingress port. Once the destination device responds, the switch can
learn its MAC address and subsequently forward frames specifically.
Question 6
A company receives the IPv4 network 192.168.100.0/24 and requires four equal-sized
subnets. Which subnetting approach is appropriate?
, A. Borrow 1 host bit and use /25
B. Borrow 2 host bits and use /26
C. Borrow 3 host bits and use /27
D. Borrow 4 host bits and use /28
🔴 Correct Answer: B. Borrow 2 host bits and use /26.
🔵 Explanation: Creating four equal subnets requires 2 borrowed bits because 2² = 4.
Increasing the prefix from /24 to /26 produces four /26 subnets, each containing 64 total
addresses and 62 normally usable host addresses.
Question 7
A technician observes that users on a switch experience severe performance
degradation only during periods of heavy broadcast activity. Unicast traffic remains
comparatively stable. Which design change would BEST address the underlying
problem?
A. Increase DNS TTL values
B. Create appropriate VLAN boundaries to reduce broadcast domains
C. Disable MAC address learning
D. Replace IPv4 with static addressing
🔴 Correct Answer: B. Create appropriate VLAN boundaries to reduce broadcast
domains.
🔵 Explanation: Broadcast traffic is contained within a Layer 2 broadcast domain. Proper
VLAN segmentation reduces the number of devices receiving broadcasts and can
substantially limit the propagation of excessive broadcast traffic.
Question 8
A network uses DHCP. After a DHCP server becomes unavailable, newly connected
clients cannot obtain addresses, but existing clients continue functioning temporarily.
Which explanation BEST accounts for this behavior?
A. Existing leases may remain valid until their lease periods expire
B. DHCP automatically converts every client to IPv6
C. Switches permanently cache DHCP leases for all clients
D. DNS automatically assigns replacement IPv4 addresses
🔴 Correct Answer: A. Existing leases may remain valid until their lease periods
expire.
