Help Center/ Virtual Private Cloud/ FAQs/ VPCs and Subnets/ How Do I Change the DNS Server Address of an ECS?
Updated on 2024-10-25 GMT+08:00
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How Do I Change the DNS Server Address of an ECS?

Scenarios

This section describes how to change the DNS server address of an ECS and make the new DNS server address take effect immediately on the ECS.

The required operations are as follows:

  1. Viewing the DNS Server Addresses for an ECS
  2. Changing the DNS Server Addresses for a VPC Subnet
  3. Changing DNS Servers for the ECS

Background

ECSs use private DNS servers for domain name resolution in VPCs. The private DNS servers do not affect the domain name resolution for the ECSs to access the Internet. Additionally, you can use the private DNS servers to directly access the private IP addresses of cloud services, such as OBS and SMN. Compared with the access through the Internet, this access features high performance and low latency.

Before private domain names are available, VPC subnets use the public DNS server (114.114.114.114). To allow ECSs in these VPCs to access private domain names, you can change the public DNS server to the private DNS servers configured for the VPC subnets. For instructions about how to obtain a private DNS server address, see What Are the Private DNS Servers Provided by the Huawei Cloud DNS Service?

Viewing the DNS Server Addresses for an ECS

  1. Log in to the management console.
  2. Choose Computing > Elastic Cloud Server.

    The Elastic Cloud Server page is displayed.

  3. In the ECS list, click the name of the target ECS.
  4. On the ECS details page, click the VPC name.

    The Virtual Private Cloud page is displayed.

  5. Locate the VPC and click the number in the Subnets column.

    The Subnets page is displayed.

  6. Click the name of the subnet.

    In the Gateway and DNS Information area, view the DNS server addresses used by the ECS.

Changing the DNS Server Addresses for a VPC Subnet

If the ECS uses default public DNS server addresses, change them to Huawei Cloud private DNS server addresses.

  1. In the Gateway and DNS Information area, click next to DNS Server Address.
  2. Change the DNS server addresses to private DNS server addresses.

Changing DNS Servers for the ECS

After you change the DNS server addresses of a VPC subnet, the DNS server addresses of ECSs in the subnet will not take effect immediately.

To make the DNS server addresses take effect immediately, do as follows:
  • Restart the OS. The ECS will then obtain the new DNS server addresses from the DHCP server.

    Restarting the OS will interrupt services on the ECS. Perform this operation during off-peak hours.

    Alternatively, wait for the DHCP lease to expire. After the lease time expires, the DHCP server allocates another IP address and updates the DNS server addresses to the ECS.

  • Obtain the new DNS server addresses.
    1. Log in to the ECS.

      For details, see Logging In to an ECS.

    2. Run the following command to view the DNS server address of the ECS:

      cat /etc/resolv.conf

      If information similar to the following is displayed, 114.114.114.114 is the DNS server address of the ECS.

    3. Run the following command to check whether the dhclient process exists:

      ps -ef | grep dhclient | grep -v grep

      If information similar to the following is displayed, no process exists (CentOS 8.1 is used as an example).

      In this case, run the dhclient command to start the process and check whether the dhclient process exists.

      If information similar to the following is displayed, process exists (CentOS 7.2 is used as an example).

    4. Run the following command to release the current DNS server address:

      dhclient -r

    5. Run the following command to restart the dhclient process and obtain new DNS server addresses:

      dhclient

    6. Run the following command to view the new DNS server addresses of the ECS:

      cat /etc/resolv.conf

      If information similar to the following is displayed, 100.125.1.250 and 100.125.64.250 are the new DNS server addresses of the ECS.

Parent topic: VPCs and Subnets