Configuring Local DHCP Pools on Autonomous IOS APs for Wireless Clients

Which local DHCP pools work without using "ip helper-address" command?

Question

Which local DHCP pools that are configured on an autonomous IOS AP will properly work and lease IP addresses to the wireless clients without using the "ip helper-address" command?

Answers

Explanations

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A. B. C. D.

A.

When a wireless client connects to an autonomous IOS AP and requests an IP address from the DHCP server, the AP can act as a DHCP server and provide IP addresses to the clients from its own local DHCP pool. However, there are certain conditions that must be met for this to work properly:

  • The DHCP pool must be configured on the AP itself. This means that the AP must have a local DHCP pool configured for the VLAN(s) where the wireless clients are connected.
  • The VLAN(s) where the wireless clients are connected must be configured on the AP. This can be done using the "switchport trunk allowed vlan" command on the AP's Ethernet interface, or by configuring the VLANs directly on the AP using the "vlan" command.
  • The AP must be configured to act as a DHCP server for the VLAN(s) where the wireless clients are connected. This can be done using the "ip dhcp pool" command on the AP, where you specify the VLAN(s) and the DHCP pool parameters (such as IP address range, default gateway, DNS server, etc.).

Given these conditions, the answer to the question is B. Only the pool configured for the VLAN assigned to the SSID where the wireless clients are connected will properly work and lease IP addresses to the wireless clients without using the "ip helper-address" command. This is because the AP will only act as a DHCP server for the VLAN(s) where the wireless clients are connected, and each SSID is typically mapped to a specific VLAN. Therefore, if you have multiple SSIDs with different VLAN assignments, you will need to configure a separate DHCP pool for each VLAN/SSID combination.

Answer A is incorrect because the native VLAN is typically used for management traffic and is not usually associated with any SSID or wireless clients. Answer C is incorrect because not all of the configured local DHCP pools may be applicable to the VLAN(s) where the wireless clients are connected. Answer D is also incorrect because static routing has no direct impact on the ability of the AP to act as a DHCP server for its local DHCP pools.