A network administrator receives alerts that newly deployed IP security cameras in a logis… — CompTIA Network+

A network administrator receives alerts that newly deployed IP security cameras in a logistics facility are unable to communicate with the central surveillance management server. Examination of a affected camera's network configuration reveals an IP address of $192.168.1.105$ with a default gateway of $192.168.1.1$ . However, the camera VLAN is defined as $10.120.45.0/24$ with leases managed by a central enterprise DHCP server at $10.100.10.50$ . Which of the following is the most likely cause of this issue?

A rogue DHCP server is connected to the camera VLAN and responding to lease requests faster than the authorized DHCP server.Answer
B
The IP helper address configured on the router interface serving the camera VLAN is pointing to an invalid DHCP server IP.
C
The cameras have automatically generated APIPA addresses due to a broadcast domain isolation failure.
D
The central DHCP scope for the 10.120.45.0/24 network has exhausted all usable host IP addresses.

Answer

The presence of a rogue DHCP server on the local subnet responding to client requests.

When network clients receive valid IP leases belonging to an incorrect subnet rather than APIPA addresses or no IP at all, an unauthorized (rogue) DHCP server attached to the local switchport segment is responding to DHCPDISCOVER broadcast packets before the legitimate remote or local DHCP server.

Step-by-Step Solution

Analyze the reported IP addressing symptoms

The client received an IP address (

192.168.1.105

) and gateway (

192.168.1.1

) belonging to a completely different subnet than the designated VLAN subnet (

10.120.45.0/24

Determining whether an address is APIPA, misconfigured statically, or leased from an unexpected range helps narrow down DHCP infrastructure issues.

Evaluate potential failure modes

Because the host received a valid (non-APIPA) DHCP lease, a DHCP server answered the DHCPDISCOVER request. Since the authorized server only distributes

10.120.45.0/24

addresses, an unauthorized server on the local broadcast domain must be answering.

DHCP discovery uses local broadcasts; the fastest DHCP OFFER response is accepted by the client host.

Select the correct root cause

A rogue DHCP server on the broadcast domain is intercepting and responding to client discovery messages.

Rogue DHCP servers (e.g., misconfigured consumer routers connected to switchports) respond with their own local pool settings.

Key Concept

Rogue DHCP Server Identification and Symptoms

Estimated Time:1m 30s

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

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