How does the AR used as the DHCP server ensure that users obtain the correct DHCP server address

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To ensure that users obtain the correct DHCP server address when the Huawei AR serves as the DHCP server, you can configure DHCP snooping on the switch or the DHCP relay agent that is closest to the users.

Other related questions:
DHCP client cannot obtain a correct IP address
The request packets (DHCP discover) are broadcast by the DHCP clients. If multiple DHCP servers are located on the same subnet (for example, bogus DHCP server), the clients may obtain IP addresses from a bogus DHCP server. To address this problem, configure DHCP snooping. Then clients can receive DHCP packets from only the trusted DHCP server. Perform the following configuration: [Huawei] dhcp enable [Huawei] dhcp snooping enable [Huawei] interface gigabitethernet 1/0/1 //Enter the view of the interface connected to the DHCP client. [Huawei-GigabitEthernet1/0/1] dhcp snooping enable [Huawei-GigabitEthernet1/0/1] quit [Huawei] interface gigabitethernet 1/0/2 [Huawei-GigabitEthernet1/0/2] dhcp snooping trusted //Configure the interface of the DHCP server as the trusted interface. [Huawei-GigabitEthernet1/0/2] quit Note: - When you configure DHCP snooping on a Layer 2 access device, steps 1, 2, and 3 are mandatory and must be performed in the following sequence. - When you configure DHCP snooping on a DHCP relay agent, only steps 1 and 2 are required.

How does an AR used as the DHCP server allocate IP addresses to many DHCP clients
When an AR functions as a DHCP server, you can enlarge the address pool range and shorten the lease of IP addresses to allow DHCP clients to quickly connect to and disconnect from the network.

DHCP clients fail to obtain IP addresses from the DHCP server on the AR
The causes that DHCP clients fail to obtain IP addresses from the DHCP server are as follows: - The configuration is incorrect. - There is no allocable IP address in the DHCP address pool. - STP is enabled on upper-level access devices of some diskless workstations. For details on troubleshooting and solutions, see AR150&AR160&AR200&AR510&AR1200&AR2200&AR3200 FAQ.
About the AR ClientExceptions occurs when the IP address is obtained. For details, see the Revelations of Troublesolving on the right page.

How is an AR used as the DHCP server enabled to record logs when the DHCP server allocates IP addresses
A Huawei AR records logs when IP addresses are allocated through DHCP. The logs are stored in a non-TXT file. Perform the following configurations: - Interface-based [Huawei] interface gigabitethernet 1/0/0 [Huawei-GigabitEthernet1/0/0] dhcp select interface [Huawei-GigabitEthernet1/0/0] dhcp server logging //Enable the DHCP server to record logs when the DHCP server allocates IP addresses. - Global mode [Huawei] ip pool global [Huawei-ip-pool-global] logging //Enable the DHCP server to record logs when the DHCP server allocates IP addresses.

Failure to obtain IP addresses from DHCP server
For S series switches (except S1700 switches), a client may fail to obtain an IP address from the DHCP server due to the following: - Incorrect configuration - No available IP address in the address pool - STP enabled on the upper-layer access device of diskless workstations For the fault locating and troubleshooting procedure, see the section "A Client Fails to Obtain an IP Address from a DHCP Server" in Configuration Guide �?IP Service.

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