Question

Difficulty: EasyMobile Device Wireless and Network Connectivity

A user reports that while connected to an enterprise Wi-Fi network, their smartphone is unable to access internal network shares or internet websites. A technician checks the smartphone's IP configuration and observes an IPv4 address of 169.254.73.201169.254.73.201 with a subnet mask of 255.255.0.0255.255.0.0. Which of the following best explains why the mobile device received this IP address?

  1. The mobile device failed to contact a DHCP server and assigned itself an APIPA address.Answer
  2. B
    The device's SIM card is provisioned with an invalid IMEI identifier required for network access.
  3. C
    The enterprise access point is operating on overlapping 2.4 GHz channels 2 and 3.
  4. D
    The mobile web browser is attempting to negotiate connection requests on port 80 instead of port 443.

Answer

The mobile device failed to contact a DHCP server and assigned itself an APIPA address.
An IPv4 address beginning with 169.254.x.x indicates Automatic Private IP Addressing (APIPA). When a mobile device joins a Wi-Fi network configured for DHCP but receives no response from a DHCP server, the operating system self-assigns a link-local APIPA address. This allows communication with other link-local devices on the same physical segment but prevents communication outside the local subnet or to the internet.

Step-by-Step Solution

1
Analyze the observed IPv4 address assigned to the mobile device.
The address 169.254.73.201169.254.73.201 falls within the 169.254.0.0/16169.254.0.0/16 range.
Addresses in the 169.254.0.0/16169.254.0.0/16 range are designated for Automatic Private IP Addressing (APIPA).
2
Determine the trigger for APIPA address generation on mobile networks.
APIPA occurs when a network client is configured for dynamic IP addressing (DHCP) but does not receive a response from a local DHCP server.
The client self-assigns an APIPA address to maintain local network link communication when DHCP services are unreachable.

Key Concept

Automatic Private IP Addressing (APIPA) in Mobile Networking
Estimated Time:45s
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