The DHCP client cannot obtain DNS information on the AR


DPossible causes are as follows:
1. The route from the AR to the DHCP server is unreachable.
2. The DNS and DHCP configuration modes are different.
When the DHCP server assigns an IP address and gateway address to a client, the DHCP server also sends the DNS server address to the client. Ensure that the DNS server address and DHCP server address are configured in the global address pool or on an interface so that the DHCP server can find the DNS server IP address and deliver it.

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.

An AR used as a DHCP client cannot obtain an IP address
When the configuration is correct, you can shorten the IP address lease. If the IP address lease is long, after addresses in the address pool are allocated, the address that has been allocated to a client is no longer used and cannot be released. As a result, other DHCP clients cannot obtain the IP address.

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.

DHCP clients cannot obtain IP addresses. How do I solve this problem
Ensure that the DHCP configuration is correct, and reduce the IP address lease. If a long IP address lease is set, after all addresses in the address pool are allocated, addresses that are not required cannot be released immediately. As a result, other DHCP clients cannot obtain IP addresses.

The PC connected to the DHCP server cannot obtain DNS information when the AR1220 serves as the PPPoE client
The AR used as the DHCP server cannot assign information about the DNS server obtained from the PPPoE server to DHCP clients. 1. Run the ppp ipcp dns admit-any command on the dialer interface to configure the AR to receive the IP address of the DNS server specified by the remote device. If the command is not configured, the AR cannot obtain DNS information. 2. DNS proxy is used to meet customers' requirements. Run the following commands in the system view: dns resolve dns proxy enable In the IP pool view, dns-list is configured as the address of the AR. In this way, the AR is equivalent to the DNS server for a PC. After receiving a DNS request, the AR sends it to the DNS server to complete domain name resolution.

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