Dynamic Host Configuration Protocol (DHCP) is a network management protocol. DHCP provides a standard for passing configuration information to servers in a TCP/IP network. You can use DHCP options sets to configure DNS server IP addresses and domain names for Elastic Compute Service (ECS) instances that are deployed in a virtual private cloud (VPC).
Feature release and supported regions
The DHCP options set feature is in public preview. To use this feature,submit a ticket.
| Area | Supported region |
|---|---|
| Asia Pacific | China (Beijing), China (Hangzhou), China (Shanghai), China (Shenzhen), China (Chengdu), China (Hong Kong) Japan (Tokyo), Singapore (Singapore), Australia (Sydney), Malaysia (Kuala Lumpur), and Indonesia (Jakarta) |
| Europe & Americas | US (Virginia), US (Silicon Valley), Germany (Frankfurt), and UK (London) |
| Middle East & India | India (Mumbai) and UAE (Dubai) |
Features
By default, the IP addresses of the Alibaba Cloud DNS servers are specified for the ECS instance that you create. The Alibaba Cloud DNS servers cannot resolve private domain names. You can specify custom DNS server IP addresses for your ECS instance. However, the custom configurations are cleared after you restart the ECS instance.
To resolve this problem, you can create a DHCP options set and associate it with a VPC. Then, newly created ECS instances in the VPC use the configurations of the DHCP options set. After the DHCP options set is synchronized with existing ECS instances, existing ECS instances also use the configurations of the DHCP options set. For more information, see How DHCP options sets are applied to ECS instances.
| DHCP option | Description |
|---|---|
| Domain name | The root domain of the ECS instance, such as example.com. |
| DNS server IP address | The IP addresses of the DNS servers.
The IP addresses of the Alibaba Cloud DNS servers, which are 100.100.2.136 and 100.100.2.138, are used by default. This ensures that you can access basic services on Alibaba Cloud. You can also specify up to four custom DNS server IP addresses to meet your business requirements.
Notice Before you specify custom DNS server IP addresses, take note of the following limits:
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How DHCP options sets are applied to ECS instances
| Instance type | Rule |
|---|---|
| Existing ECS instances (ECS instances that are created in the VPC before the DHCP options set is associated with the VPC). | If one of the following operations is performed, the DHCP options are synchronized to the existing ECS instances in the VPC.
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| New ECS instances (ECS instances that are created in the VPC after the DHCP options set is associated with the VPC). | No operation is required to trigger the synchronization. The DHCP options are automatically synchronized to the newly created ECS instances in the VPC. |
Limits
| Item | Default limit | Quota increase |
|---|---|---|
| Number of DHCP options sets that can be created with each Alibaba Cloud account | 10 | N/A |
| Number of VPCs that can be associated with each DHCP options set | 10 | |
| Number of DHCP options sets that can be associated with each VPC | 1 | |
| Number of domain names that can be specified in each DHCP options set | 1 | |
| Number of DNS server IP addresses that can be specified in each DHCP options set | 4 | |
| VPCs that cannot be associated with DHCP options sets | VPCs that contain ECS instances of the following instance families: ecs.c1, ecs.c2, ecs.c4, ecs.ce4, ecs.cm4, ecs.d1, ecs.e3, ecs.e4, ecs.ga1, ecs.gn4, ecs.gn5, ecs.i1, ecs.m1, ecs.m2, ecs.mn4, ecs.n1, ecs.n2, ecs.n4, ecs.s1, ecs.s2, ecs.s3, ecs.se1, ecs.sn1, ecs.sn2, ecs.t1, and ecs.xn4. For more information, see Advanced VPC features. |
Upgrade or release an Elastic Compute Service (ECS) instance that does not support advanced network features.
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Work with DHCP options sets
For more information, see Work with DHCP options sets.