Page 1 of 178
CISCO CCNA PRACTICE EXAMS
COMPREHENSIVE TEST BANK
250+ MULTIPLE-CHOICE QUESTIONS WITH
DETAILED RATIONALES
2026-2027 ACADEMIC YEAR EDITION
itsjereguides
# Table Of Contents
## Section 1: Network Infrastructure And Connectivity (Questions 1-50)
## Section 2: Switching And Network Access (Questions 51-100)
## Section 3: Ip Routing (Questions 101-150)
## Section 4: Network Services And Security (Questions 151-200)
## Section 5: Ai, Network Operations And Management (Questions 201-250)
,Page 2 of 178
# SECTION 1: NETWORK INFRASTRUCTURE AND CONNECTIVITY
## Questions 1-50
**Question 1**
An administrator notices excessive CRC errors on a Gigabit Ethernet link. What is the MOST
likely cause of this issue?
A. An incorrect VLAN assignment
B. A duplex mismatch between the connected devices
C. An IP addressing conflict on the network
D. A spanning-tree loop blocking the interface
**Correct Answer: B**
**Rationale:** CRC errors are typically caused by physical layer issues, with duplex mismatch
being one of the most common causes . When one device operates at full duplex and the other at
half duplex, collisions and CRC errors increase dramatically. This is a core troubleshooting
concept in CCNA .
**Why Others Are Incorrect:**
- A: VLAN assignment issues affect Layer 2 connectivity but do not cause CRC errors
- C: IP conflicts cause communication issues but not physical layer errors
- D: STP blocking prevents traffic but does not cause CRC errors
---
**Question 2**
Which of the following IPv6 address types is used for communication within a single subnet and
is not routable beyond that subnet?
,Page 3 of 178
A. Global Unicast
B. Unique Local
C. Link-Local
D. Multicast
**Correct Answer: C**
**Rationale:** Link-Local addresses (FE80::/10) are used for communication within a single
subnet and are never routed beyond the local link . Routers will not forward packets with Link-
Local source or destination addresses .
**Why Others Are Incorrect:**
- A: Global Unicast addresses are globally routable on the IPv6 Internet
- B: Unique Local addresses are routable within an organization but not on the public Internet
- D: Multicast addresses are used for one-to-many communication and can be routed
---
**Question 3**
A network engineer is configuring a router to forward packets between VLAN 10 and VLAN 20
using router-on-a-stick. Which interface configuration is required?
A. Two physical interfaces, each assigned to a different VLAN
B. A single physical interface with multiple subinterfaces, each with a unique VLAN ID
C. A single physical interface with an IP address and no VLAN configuration
D. A Layer 3 switch interface with an SVI for each VLAN
**Correct Answer: B**
, Page 4 of 178
**Rationale:** Router-on-a-stick uses a single physical interface with multiple subinterfaces,
each configured with a unique VLAN ID using 802.1Q encapsulation . The subinterfaces are
assigned IP addresses in their respective VLAN subnets .
**Why Others Are Incorrect:**
- A: Two physical interfaces would work but is not the router-on-a-stick method
- C: A single interface without VLAN configuration would not support multiple VLANs
- D: SVIs are used on Layer 3 switches, not routers
---
**Question 4**
What is the administrative distance of OSPF?
A. 1
B. 90
C. 110
D. 120
**Correct Answer: C**
**Rationale:** OSPF has an administrative distance of 110 . Administrative distance is the
trustworthiness of a routing source, with lower values being preferred .
**Why Others Are Incorrect:**
- A: 1 is the AD for a directly connected interface
- B: 90 is the AD for EIGRP
- D: 120 is the AD for RIP
CISCO CCNA PRACTICE EXAMS
COMPREHENSIVE TEST BANK
250+ MULTIPLE-CHOICE QUESTIONS WITH
DETAILED RATIONALES
2026-2027 ACADEMIC YEAR EDITION
itsjereguides
# Table Of Contents
## Section 1: Network Infrastructure And Connectivity (Questions 1-50)
## Section 2: Switching And Network Access (Questions 51-100)
## Section 3: Ip Routing (Questions 101-150)
## Section 4: Network Services And Security (Questions 151-200)
## Section 5: Ai, Network Operations And Management (Questions 201-250)
,Page 2 of 178
# SECTION 1: NETWORK INFRASTRUCTURE AND CONNECTIVITY
## Questions 1-50
**Question 1**
An administrator notices excessive CRC errors on a Gigabit Ethernet link. What is the MOST
likely cause of this issue?
A. An incorrect VLAN assignment
B. A duplex mismatch between the connected devices
C. An IP addressing conflict on the network
D. A spanning-tree loop blocking the interface
**Correct Answer: B**
**Rationale:** CRC errors are typically caused by physical layer issues, with duplex mismatch
being one of the most common causes . When one device operates at full duplex and the other at
half duplex, collisions and CRC errors increase dramatically. This is a core troubleshooting
concept in CCNA .
**Why Others Are Incorrect:**
- A: VLAN assignment issues affect Layer 2 connectivity but do not cause CRC errors
- C: IP conflicts cause communication issues but not physical layer errors
- D: STP blocking prevents traffic but does not cause CRC errors
---
**Question 2**
Which of the following IPv6 address types is used for communication within a single subnet and
is not routable beyond that subnet?
,Page 3 of 178
A. Global Unicast
B. Unique Local
C. Link-Local
D. Multicast
**Correct Answer: C**
**Rationale:** Link-Local addresses (FE80::/10) are used for communication within a single
subnet and are never routed beyond the local link . Routers will not forward packets with Link-
Local source or destination addresses .
**Why Others Are Incorrect:**
- A: Global Unicast addresses are globally routable on the IPv6 Internet
- B: Unique Local addresses are routable within an organization but not on the public Internet
- D: Multicast addresses are used for one-to-many communication and can be routed
---
**Question 3**
A network engineer is configuring a router to forward packets between VLAN 10 and VLAN 20
using router-on-a-stick. Which interface configuration is required?
A. Two physical interfaces, each assigned to a different VLAN
B. A single physical interface with multiple subinterfaces, each with a unique VLAN ID
C. A single physical interface with an IP address and no VLAN configuration
D. A Layer 3 switch interface with an SVI for each VLAN
**Correct Answer: B**
, Page 4 of 178
**Rationale:** Router-on-a-stick uses a single physical interface with multiple subinterfaces,
each configured with a unique VLAN ID using 802.1Q encapsulation . The subinterfaces are
assigned IP addresses in their respective VLAN subnets .
**Why Others Are Incorrect:**
- A: Two physical interfaces would work but is not the router-on-a-stick method
- C: A single interface without VLAN configuration would not support multiple VLANs
- D: SVIs are used on Layer 3 switches, not routers
---
**Question 4**
What is the administrative distance of OSPF?
A. 1
B. 90
C. 110
D. 120
**Correct Answer: C**
**Rationale:** OSPF has an administrative distance of 110 . Administrative distance is the
trustworthiness of a routing source, with lower values being preferred .
**Why Others Are Incorrect:**
- A: 1 is the AD for a directly connected interface
- B: 90 is the AD for EIGRP
- D: 120 is the AD for RIP
