Interconnecting Cisco Networking Devices Part 1 (ICND1) 100-105 — Questions and Answers

Question 1: Which command would you use to verify that CDP neighbors are being detected on a Cisco switch?

show mac-address-table
show cdp neighbors (Correct answer)
show ip neighbors
show arp neighbors

Correct answer: show cdp neighbors

'show cdp neighbors' displays directly connected Cisco devices discovered via the Cisco Discovery Protocol.

Question 2: Which foundational principle is MOST important for success in the Interconnecting Cisco Networking Devices Part 1 profession?

Maintaining the minimum requirements for certification
Maximizing financial returns on every engagement
Specializing in only one narrow area of practice
Commitment to continuous learning, ethical practice, and quality outcomes (Correct answer)

Correct answer: Commitment to continuous learning, ethical practice, and quality outcomes

Success in any professional field requires a commitment to continuous learning to stay current, ethical practice to maintain trust and integrity, and a focus on quality outcomes that serve stakeholders and the public interest.

Question 3: Which Syslog level should be configured on a production router to capture only critical events without overwhelming the logging system?

Level 7 (Debug)
Level 3 (Errors) (Correct answer)
Level 6 (Informational)
Level 0 (Emergencies)

Correct answer: Level 3 (Errors)

Level 3 (Errors) captures Emergencies, Alerts, Critical, and Error messages while filtering out less critical informational and debug messages.

Question 4: Which of the following is a private IP address?

8.8.8.8
172.256.256.256
64.233.160.0
192.168.1.1 (Correct answer)

Correct answer: 192.168.1.1

Private IP addresses are specifically reserved for use within local networks and are not routable on the public internet. The range 192.168.0.0 to 192.168.255.255 is one of the designated private IP address ranges, making 192.168.1.1 a classic example used in many home and office networks.

Question 5: What is the main benefit of subnetting in IP addressing?

It makes the network easier to manage and secure (Correct answer)
It speeds up the internet connection.
It reduces the number of available IP addresses.
It eliminates the need for routers.

Correct answer: It makes the network easier to manage and secure

Subnetting involves dividing a larger IP network into smaller, more manageable subnetworks. This practice improves network efficiency by reducing broadcast traffic, enhances security by isolating network segments, and simplifies network administration and IP address management.

Question 6: A switch port is configured as 'switchport mode access' on VLAN 20. Which statement is true?

The port negotiates trunking with the connected device
The port can belong to multiple VLANs simultaneously
The port carries untagged frames belonging to VLAN 20 (Correct answer)
The port carries tagged frames for VLAN 20

Correct answer: The port carries untagged frames belonging to VLAN 20

Access ports carry untagged Ethernet frames; the switch internally assigns those frames to the configured access VLAN.

Question 7: What is the purpose of the Management Information Base (MIB) in SNMP?

Stores SNMP community strings for authentication
Defines the hierarchical database of managed objects on a device (Correct answer)
Provides encryption keys for SNMPv3
Maps IP addresses to SNMP agent ports

Correct answer: Defines the hierarchical database of managed objects on a device

The MIB is a structured database that defines all the variables (objects) that can be monitored or configured via SNMP.

Question 8: What happens when a RIP router receives a route update advertising a destination with a hop count of 16?

It installs the route with metric 16
It treats the destination as unreachable and discards the route (Correct answer)
It resets the hop count to 15 before installing
It requests an alternative path via a query message

Correct answer: It treats the destination as unreachable and discards the route

In RIP, a hop count of 16 represents infinity, meaning the destination is unreachable and the route is not installed.

Question 9: What does the 802.1Q tag inserted into an Ethernet frame contain?

Destination IP and VLAN ID only
Source MAC, VLAN ID, and CoS bits
VLAN ID, subnet mask, and frame checksum
VLAN ID and a 3-bit priority field (CoS) (Correct answer)

Correct answer: VLAN ID and a 3-bit priority field (CoS)

The 4-byte 802.1Q tag includes a 12-bit VLAN ID (supporting VLANs 1–4094) and a 3-bit Class of Service (CoS) priority field.

Question 10: What is the MOST effective way for new ICND1 professionals to build competency in their field?

Learning entirely through trial and error
Studying certification materials exclusively
Focusing solely on the most advanced topics
Combining formal education, mentored practice, and ongoing professional development (Correct answer)

Correct answer: Combining formal education, mentored practice, and ongoing professional development

Building professional competency requires a multi-faceted approach: formal education provides foundational knowledge, mentored practice develops applied skills under guidance, and ongoing professional development ensures continuous growth and currency in the field.

Question 11: What is the default bridge priority value used in Spanning Tree Protocol?

65535
32768 (Correct answer)
4096
8192

Correct answer: 32768

The default STP bridge priority is 32768 on all Cisco switches unless manually changed.

Question 12: Which NTP stratum level is assigned to devices that synchronize directly from an atomic clock or GPS source?

Stratum 1 (Correct answer)
Stratum 0
Stratum 15
Stratum 2

Correct answer: Stratum 1

Stratum 1 devices synchronize directly from a Stratum 0 reference clock (atomic/GPS) and serve as primary NTP servers.

Question 13: Which file system location stores the Cisco IOS image on most routers?

Flash (Correct answer)
ROM
RAM
NVRAM

Correct answer: Flash

The IOS image is stored in Flash memory, which is non-volatile and retains content after power loss.

Question 14: What is the function of the 'established' keyword in an extended ACL?

Permits only ICMP echo replies
Enables stateful inspection on the router
Permits TCP packets that are part of an existing session (ACK or RST set) (Correct answer)
Blocks new TCP connections while allowing UDP

Correct answer: Permits TCP packets that are part of an existing session (ACK or RST set)

The 'established' keyword matches TCP packets with ACK or RST flags set, indicating they belong to an existing connection.

Question 15: Which approach best demonstrates mastery of troubleshooting in ICND1 practice?

Applying principles to novel situations with sound judgment (Correct answer)
Avoiding complex scenarios
Following procedures without understanding
Relying entirely on technology

Correct answer: Applying principles to novel situations with sound judgment

True mastery involves understanding underlying principles well enough to apply them to new and unfamiliar situations with professional judgment.

Question 16: What is the MOST important factor to consider when selecting assessment tools for ICND1 certification work?

The cost of the assessment tool
Personal familiarity with the tool
How quickly the tool can be administered
Validity, reliability, and appropriateness for the specific context (Correct answer)

Correct answer: Validity, reliability, and appropriateness for the specific context

Assessment tools must be valid (measuring what they claim to measure), reliable (producing consistent results), and appropriate for the specific context and population. These psychometric properties ensure the quality of assessment outcomes.

Question 17: When configuring inter-VLAN routing on a Layer 3 switch, which command enables IP routing globally?

switchport ip routing on
router vlan
enable routing
ip routing (Correct answer)

Correct answer: ip routing

The global configuration command 'ip routing' enables the Layer 3 switch to perform IP routing between VLAN interfaces (SVIs).

Question 18: A Cisco device sends an unsolicited SNMP message to the NMS when an interface goes down. What is this message called?

SNMP Set
SNMP Trap (Correct answer)
SNMP Get
SNMP Inform

Correct answer: SNMP Trap

An SNMP Trap is an unsolicited notification sent from the agent to the NMS when a significant event occurs.

Question 19: Which command verifies that SSH version 2 is configured on a Cisco device?

show ip ssh (Correct answer)
show crypto ssh
show service ssh
show ssh version

Correct answer: show ip ssh

The 'show ip ssh' command displays the SSH version, authentication timeout, and retry settings configured on the Cisco device.

Question 20: Which foundational principle is MOST important for success in the Interconnecting Cisco Networking Devices Part 1 profession?

Maintaining the minimum requirements for certification
Commitment to continuous learning, ethical practice, and quality outcomes (Correct answer)
Specializing in only one narrow area of practice
Maximizing financial returns on every engagement

Correct answer: Commitment to continuous learning, ethical practice, and quality outcomes

Question 21: Which debug command would help identify why OSPF neighbor adjacencies are not forming?

debug ip nat
debug ip packet
debug ip ospf adj (Correct answer)
debug ip rip

Correct answer: debug ip ospf adj

'debug ip ospf adj' shows OSPF adjacency events and error messages that explain why neighbor relationships fail to establish.

Question 22: Which Cisco IOS command displays the Layer 2 to Layer 3 address mappings learned by a router?

show ip arp (Correct answer)
show ip route
show cdp neighbors detail
show mac-address-table

Correct answer: show ip arp

'show ip arp' displays the ARP cache, which maps IP addresses to MAC addresses on connected segments.

Question 23: Which network address belongs to the same /27 subnet as host 192.168.5.100?

192.168.5.96 (Correct answer)
192.168.5.128
192.168.5.64
192.168.5.112

Correct answer: 192.168.5.96

A /27 has a block size of 32; 96 ≤ 100 < 128, so the network address is 192.168.5.96.

Question 24: Which device operates at Layer 1 and simply regenerates the electrical signal?

Bridge
Router
Hub (Correct answer)
Switch

Correct answer: Hub

A hub is a Layer 1 device that repeats electrical signals out all ports without any intelligence.

Question 25: Which attack technique allows a host to send frames on a VLAN it should not access by exploiting trunk negotiation?

MAC flooding
VLAN hopping via double tagging (Correct answer)
STP root takeover
ARP poisoning

Correct answer: VLAN hopping via double tagging

Double-tagging attacks embed an inner VLAN tag that gets processed after the outer tag is stripped at the first trunk.

Question 26: Which protocol and port does SNMP use for NMS-to-agent queries?

UDP port 161 (Correct answer)
UDP port 162
TCP port 162
TCP port 161

Correct answer: UDP port 161

SNMP uses UDP port 161 for NMS-to-agent queries (Get/Set), while traps and informs use UDP port 162.

Question 27: Which spanning tree port state listens for BPDUs but neither learns MAC addresses nor forwards frames?

Learning
Blocking
Listening (Correct answer)
Disabled

Correct answer: Listening

The Listening state processes BPDUs to determine topology but does not populate the MAC table or forward data.

Question 28: Which feature prevents a non-root switch port from immediately transitioning to forwarding when it first connects, avoiding temporary loops?

Spanning Tree Protocol (Correct answer)
Root Guard
BPDU Guard
Loop Guard

Correct answer: Spanning Tree Protocol

STP's listening and learning states introduce a delay before forwarding to ensure a loop-free topology is established.

Question 29: A host sends a packet to 255.255.255.255. What kind of message is this?

Directed broadcast
Unicast
Multicast
Limited broadcast (Correct answer)

Correct answer: Limited broadcast

255.255.255.255 is the limited broadcast address, delivered to all hosts on the local network segment only.

Question 30: What command correctly assigns an access port to VLAN 20 on a Cisco switch?

vlan access 20
switchport mode vlan 20
switchport vlan 20
switchport access vlan 20 (Correct answer)

Correct answer: switchport access vlan 20

The command 'switchport access vlan 20' assigns the interface to VLAN 20 as an access port.

Interconnecting Cisco Networking Devices Part 1 (ICND1) 100-105

The ICND1 (100-105) exam, associated with the Cisco CCENT certification, tests foundational knowledge of network fundamentals, LAN switching, routing, infrastructure services, and infrastructure maintenance. The exam has been retired by Cisco and replaced by the consolidated CCNA 200-301.

Questions

90 min

Time Limit

83%

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