A network administrator receives reports that newly arriving wireless clients on a high-de… — CompTIA Network+

A network administrator receives reports that newly arriving wireless clients on a high-density office VLAN ( $192.168.32.0/23$ ) are unable to access network resources. Inspecting an affected workstation via `ipconfig /all` reveals the following output:

text
IPv4 Address. . . . . . . . . . . : 169.254.112.45
Subnet Mask . . . . . . . . . . . : 255.255.0.0
Default Gateway . . . . . . . . . :
DHCP Server . . . . . . . . . . . :

Wireless 802.1X authentication logs show that clients authenticate successfully, but DHCP lease requests time out. Further inspection of the centralized DHCP server shows that the scope for $192.168.32.0/23$ has $508$ active leases out of $508$ total allocated addresses, with a default lease duration of $8$ days.

Which of the following actions is the most appropriate resolution to fix the IP address assignment failure?

A
Configure a local DHCP relay agent on the wireless access points to assign APIPA addresses automatically.
Reduce the DHCP scope lease duration and expand the available address pool for the wireless VLAN.Answer
C
Change the default gateway setting in the DHCP scope options to match the client's current 169.254.x.x address range.
D
Increase the subnet mask on the DHCP scope to /24 to create additional usable host IP addresses within the scope.

Answer

Reduce the DHCP scope lease duration and expand the available address pool for the wireless VLAN.

The client terminal output shows an APIPA address (

169.254.112.45

), confirming that the client failed to receive a DHCP response. The DHCP server statistics confirm that all

508

usable addresses in the

192.168.32.0/23

pool are in use. Because the environment is high-density wireless and has an excessively long

8

-day lease time, addresses are held long after devices leave the network. Reducing lease duration and increasing the pool capacity addresses the root cause of scope exhaustion.

Step-by-Step Solution

Analyze client IP configuration

The presence of an IPv4 address in the

169.254.0.0/16

range (

169.254.112.45

) with no default gateway indicates an Automatic Private IP Addressing (APIPA) self-assignment resulting from a failed DHCP request.

When a client fails to receive a response to its DHCPDISCOVER broadcast, the operating system self-assigns an APIPA address to maintain local link connectivity.

Evaluate DHCP server logs and scope state

The server logs show

508

out of

508

addresses in the

192.168.32.0/23

scope are currently leased.

/23

subnet provides

2^{32-23} - 2 = 510 - 2 = 508

usable host addresses. Having

508

active leases indicates total DHCP scope exhaustion.

Determine corrective action for high-density wireless environments

Long lease durations (

8

days) in transient or high-density wireless environments prevent IP addresses from recycled back into the pool. Reducing the lease duration (e.g., to several hours) and expanding the IP range resolves exhaustion.

Shorter lease times reclaim IP addresses from disconnected transient devices, ensuring available capacity for incoming clients.

Key Concept

DHCP Scope Exhaustion and Lease Duration Tuning

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

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