A network technician is investigating a connectivity issue where a host with IP address 17… — CompTIA Network+

A network technician is investigating a connectivity issue where a host with IP address $172.16.5.25/24$ cannot access services on a remote subnet $10.10.1.0/24$ . Local ping tests confirm the host can communicate with other devices on $172.16.5.0/24$ . Which of the following misconfigurations could cause this issue? (Select TWO.)

The host is configured with a default gateway address ( $172.16.4.1$ ) that resides outside its assigned subnetAnswer
An Access Control List (ACL) applied to the egress router interface drops traffic due to an implicit deny ruleAnswer
C
The host and its local router interface reside within the same VLAN broadcast domain
D
The router has disabled application port 23, preventing basic Layer 3 IP packet forwarding

Answer

The host is configured with a default gateway address outside its subnet (

172.16.4.1

), and an Access Control List (ACL) drops the traffic due to an implicit deny rule.

For a host to reach remote networks, its default gateway must be on the local subnet (

172.16.5.0/24

). A gateway address of

172.16.4.1

prevents routing. Furthermore, network traffic passed to a router will be dropped if an applied ACL lacks a permit entry due to the default implicit deny clause.

Step-by-Step Solution

Analyze local vs. remote connectivity symptoms

The host communicates locally on

172.16.5.0/24

, confirming Layer 1/2 functionality and local switchport settings, but fails to reach remote networks.

Traffic destined for off-link addresses (

10.10.1.0/24

) must be sent to a valid local Layer 3 default gateway.

Evaluate default gateway IP configuration

An IP of

172.16.4.1

is on a different subnet than

172.16.5.25/24

Hosts cannot resolve ARP for a default gateway that is not on their local IP subnet, preventing remote packet delivery.

Evaluate router ACL behavior

Traffic matching no explicit permit rule on a router interface is blocked.

Access Control Lists filtering traffic implement an implicit deny rule at the end of the list.

Key Concept

Troubleshooting Default Gateways and Router ACL Placement

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

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