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This page has 5 Router R1 Cannot Reach R3 Practice Questions scenario questions for the CLCOR exam, each with detailed explanations and wrong-answer analysis.

How should I approach CLCOR scenario questions?

Read the full scenario before looking at the answer options. Identify the constraint or requirement in the scenario, then eliminate options that are generally true but wrong for this specific case. Scenario questions reward careful reading over pattern matching.

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Scenario-based practice

Router R1 Cannot Reach R3 Practice Questions

Practise identifying common networking hardware like routers, switches, access points, and their roles in a network.

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Scenario guide

How to approach router r1 cannot reach r3 practice questions

Practise routing and connectivity troubleshooting scenarios involving R1, R2, R3, static routes, OSPF, next hops and routing tables.

Quick answer

Tests identification, purpose, and configuration of routers, switches, access points, and patch panels.

Identify routers, switches, and access points by function

Understand PoE and PoE+ power requirements

Differentiate managed vs unmanaged switches

Recognize cable types: Cat5e, Cat6, fiber

Practice scenarios

Question 1hardmultiple choice

Review the full routing breakdown →

You have implemented 'Local Route Group' in your dial plan. What is the main advantage of using this instead of static Route Groups?

A
It forces the use of G.729.
Why it fails: Codec selection is governed by regions.
B
It requires less CPU on the CUCM.
Why it fails: Local Route Group is a configuration abstraction resolved at call routing time; it adds a lookup rather than removing processing, so CUCM CPU load is not reduced. It is tempting because consolidating route patterns cuts administrative overhead, and lower CPU would be the aim on an overloaded cluster.
C
It simplifies the dial plan by removing the need for location-specific route patterns.
Local Route Group assigns a route group per device pool, so a single route pattern references a logical group that resolves to the correct gateway at each location. This removes the need for location-specific route patterns, satisfying the simplification stated in the stem.
D
It allows faster call setup.
Why it fails: Local Route Group changes which gateway or route list a device selects based on its device pool, not the signalling path length, so call setup timing is unchanged. It is tempting because dial-plan lookups add latency, and reducing that would be the goal when hunting slow post-dial delay.

Full breakdown with real-world context →

Question 2hardmultiple choice

Review the full routing breakdown →

You are configuring a Cisco IOS router to perform traffic shaping for voice traffic. Why is traffic shaping often used in conjunction with queuing?

A
To prioritize voice over data traffic
Why it fails: Prioritising voice is the job of a queuing or low-latency queuing policy applied to the shaped traffic; shaping itself only enforces a rate by buffering and delaying excess packets. It is tempting because voice deployments combine both, but marking and class-based scheduling, not shaping, deliver the priority treatment.
B
To reduce the CPU utilization of the router
Why it fails: Shaping smooths bursts by buffering excess packets, which itself consumes memory and processing; CPU relief comes from offloading or hardware queuing, not shaping. It is tempting because shaping and queuing are deployed together for voice QoS, but the pairing exists to control jitter and delay, not to lower router CPU load.
C
To prevent interface congestion by smoothing out traffic bursts
Shaping smooths bursts by buffering excess packets and releasing them at the configured rate, so the interface queue is not overwhelmed by sudden spikes. This directly satisfies the stem's voice-traffic constraint: steady pacing keeps delay and jitter low, letting queuing mechanisms schedule voice reliably.
D
To increase the total throughput of the interface
Why it fails: Shaping constrains egress to a configured rate by buffering and delaying packets; pairing it with queuing orders those delayed packets, which cannot raise the physical interface's line-rate capacity. Throughput gains are tempting because smoothing bursts reduces drops and retransmissions, but that is an application-visible effect, not increased interface bandwidth.

Full breakdown with real-world context →

Question 3hardmultiple choice

Full question →

Which statement best describes the difference between policing and shaping?

A
Policing drops traffic, whereas shaping buffers it
Policing enforces a rate limit by discarding excess packets immediately, causing retransmissions and TCP throughput collapse. Shaping instead queues and delays outbound traffic to smooth bursts, avoiding drops. The stem's contrast hinges on this drop-versus-buffer mechanism, making the statement accurate.
B
Policing buffers traffic, whereas shaping drops it
Why it fails: The roles are reversed: policing drops traffic exceeding the rate, while shaping buffers and delays it. It is tempting because both mechanisms act on excess traffic, and this statement would be correct if the terms were swapped, describing shaping as the buffering mechanism and policing as the dropping one.
C
Both use buffers to manage congestion
Why it fails: Both mechanisms do use buffers, but that shared trait does not describe their difference, so the statement answers the wrong question. It is tempting because buffering is genuinely central to shaping, and this statement would be correct if the question asked what policing and shaping have in common rather than how they differ.
D
Both are applied only on ingress interfaces
Why it fails: Policing and shaping can both be applied to egress interfaces, so restricting them to ingress is factually wrong. It is tempting because many QoS deployments place policing inbound, and this statement would be correct only if the question asked about a specific platform whose policers are ingress-only.

Full breakdown with real-world context →

Question 4mediummultiple choice

Read the full DHCP explanation →

A Cisco IP Phone 8845 registered to CUCM is not receiving its configuration file from the TFTP server after a factory reset. The phone has received its IP address via DHCP and can ping the TFTP server. Which option in the DHCP scope must be configured to allow the phone to locate the TFTP server?

A
Option 42
Why it fails: Option 42 specifies NTP servers. While time synchronization is important for phone operation, it does not provide the TFTP server address needed for configuration file download. The phone can still function without NTP initially, but it cannot obtain its configuration without the TFTP server information.
B
Option 66
Why it fails: Option 66 is used for the TFTP server name (a string), but Cisco IP Phones primarily use option 150 for the TFTP server IP address. While option 66 can be used, it is not the standard for Cisco phones and may not be recognized by all models. In this scenario, the phone requires the specific Cisco-proprietary option 150.
C
Option 3
Why it fails: Option 3 is the default gateway. The phone already has network connectivity and can ping the TFTP server, indicating that the default gateway is correctly configured. Option 3 does not provide the TFTP server address, so it is not the missing piece.
D
Option 150
Option 150 provides the TFTP server address to Cisco IP Phones. Without it, the phone cannot locate the TFTP server to download its configuration file. This is the correct answer because the phone has network connectivity but lacks the TFTP server information, which is typically delivered via DHCP option 150 in Cisco environments.

Full breakdown with real-world context →

Question 5easymultiple choice

Full question →

A network engineer is troubleshooting a Cisco IP Phone 7841 that fails to register with CUCM. The phone displays 'Configuring IP' and then 'Registering'. The engineer verifies that the phone has obtained an IP address and can ping the TFTP server. Which protocol does the phone use to download its configuration file from the TFTP server?

A
FTP
Why it fails: FTP is not used by Cisco IP Phones for configuration file downloads in a CUCM environment. While FTP can be used for file transfers, it is not the protocol employed during the phone boot process. The phone relies on TFTP to retrieve its configuration from the CUCM TFTP service, making FTP an incorrect choice for this scenario.
B
HTTPS
Why it fails: HTTPS is used for secure web access and for some phone services, but it is not the protocol used for initial configuration file download from CUCM. The phone uses TFTP for this purpose. In this scenario, the phone is stuck at the registration phase, indicating it may have failed to download its configuration via TFTP, not HTTPS.
C
HTTP
Why it fails: HTTP is used for web-based provisioning or for phones that support HTTP configuration, but Cisco IP Phones in a CUCM environment primarily use TFTP to download configuration files. In this scenario, the phone is attempting to register with CUCM, which relies on TFTP for initial configuration retrieval. HTTP would not be the protocol used for this specific step.
D
TFTP
Cisco IP Phones use TFTP to download their configuration files from the CUCM TFTP server. After obtaining an IP address and discovering the TFTP server via DHCP Option 150, the phone requests its configuration file (e.g., SEP<MAC>.cnf.xml) using TFTP. This file contains the CUCM server addresses and other settings needed for registration. Without successful TFTP download, the phone cannot proceed to register.

Full breakdown with real-world context →

These CLCOR practice questions are part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style CLCOR questions with detailed explanations, topic-based practice, mock exams, readiness tracking, and study analytics.

Router R1 Cannot Reach R3 Practice Questions

How to approach router r1 cannot reach r3 practice questions

Quick answer

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Practice scenarios

You have implemented 'Local Route Group' in your dial plan. What is the main advantage of using this instead of static Route Groups?

You are configuring a Cisco IOS router to perform traffic shaping for voice traffic. Why is traffic shaping often used in conjunction with queuing?

Which statement best describes the difference between policing and shaping?

A Cisco IP Phone 8845 registered to CUCM is not receiving its configuration file from the TFTP server after a factory reset. The phone has received its IP address via DHCP and can ping the TFTP server. Which option in the DHCP scope must be configured to allow the phone to locate the TFTP server?