Point a Domain to Your Website Using an A Record - Alibaba Cloud DNS

This topic explains how to map a domain name to your website so that users can access it using the domain name.

Terms

Basic flow of browsing a webpage: When you enter a domain name in a browser, the browser uses the Domain Name System (DNS) to find the corresponding IP address. The browser then accesses the IP address to retrieve the webpage.

What is DNS and why is it needed?

DNS is a service that translates human-readable domain names into machine-readable IP addresses. Computers require an IP address to locate a target service on the network.

How does DNS know the IP address for a domain name?

A mapping between a domain name and an IP address is configured in DNS. This mapping is a DNS record. During domain name resolution, DNS-based dynamic resolution returns the IP address.

For more information, see Basic Concepts.

Your first task

Configure a DNS record to point your domain name to an IP address.

Prerequisites

Purchase an unregistered domain name, such as your-domain.com, on Alibaba Cloud Domain Names and complete domain name identity verification. If your server is in the Chinese mainland, you must also complete website ICP filing in advance.
You need an active public IP address, such as the public IP address of an ECS instance.

Quick configuration

Go to the Alibaba Cloud DNS - Authoritative Zone page. Find the domain name that you purchased, and then click the domain name or Settings to go to the Settings page.

Click Add Record and complete the form.

Parameter	Recommended value	Description
Record Type	`A`	Points the domain name to an IPv4 address.
Hostname	`www`	If the domain name is `your-domain.com`, you can access the website at `www.your-domain.com` after the configuration is successful.
Record Value	`106.12.XX.XX`	Enter the IP address that you prepared. Note If you do not have a website or an accessible IP address and only want to test the configuration process, you can enter any IP address.

Keep the default values for other parameters.

On the Settings page, verify that the new DNS record is added and that its Status is Enable.

Verification

A new record usually takes effect immediately. A change to an existing record takes effect after its Time to Live (TTL) period expires. The default TTL is 10 minutes. You can verify the configuration in the following ways:

1. Parsing and authentication

Objective: To verify that the parsing result is as expected.

Verification method:

Use the network probe tool:
1. Go to the network probe tool. Enter the domain name, such as www.your-domain.com. In the advanced configuration, specify the DNS server address as ns1.alidns.com. Check whether the IP address returned by the network probe is the same as the one you configured. If it is, the authoritative DNS resolution is working correctly.
2. Run the network probe again without specifying a DNS server. Check whether the IP address of the detection point is the same as the one you configured. If it is, the DNS record has taken effect on the local DNS servers.
Troubleshooting
Analyze the probe results:
- The result of the first network probe is not as expected
  The DNS record may be configured incorrectly. Check the Hostname and Record Value of the DNS record. Confirm that the source of the resolution request is set to Default.
- Some results of the second network probe are correct and some are incorrect
  The local DNS server of the detection node has a cached, outdated DNS record. Wait for the local DNS cache to expire (which is typically 10 minutes) and then retry.
- All results of the second network probe are incorrect
  Confirm that the domain name was purchased from Alibaba Cloud and that its DNS server status is Normal. The issue may be caused by an incorrect DNS server configuration or a locked domain name. For more information, see View and handle the abnormal status of a DNS server.
Use the command line: On your computer, open a terminal or command-line tool and run the following command. Check if the returned IP address matches the DNS record that you configured. Replace www.your-domain.com with your domain name.
```
# For Windows
# nslookup <domain_to_query> <dns_server>
nslookup www.your-domain.com ns1.alidns.com # Check if the resolution result from the specified DNS server is as expected.
nslookup www.your-domain.com # Check if the resolution result from the local DNS is as expected.

# For Linux
# dig @<dns_server> <domain_to_query>
dig @ns1.alidns.com www.your-domain.com # Check if the resolution result from the specified DNS server is as expected.
dig www.your-domain.com # Check if the resolution result from the local DNS is as expected.
```
Troubleshooting
If the resolution result is not as expected, the possible causes are as follows:
- The DNS record is configured incorrectly. Check the Hostname and Record Value of the DNS record. Confirm that the source of the resolution request is set to Default.
- Your on-premises network or Internet Service Provider (ISP) may have intercepted or redirected the DNS requests. Use the network probe tool to check if the DNS record is configured correctly from an external detection point.

2. Verify the website

Objective: Ensure that you can open the webpage by entering the domain name in a browser. Note: If you verify the website, make sure that the record value points to the IP address of an accessible web service.

Verification method:

Browser access: In a browser, access the domain name, such as http://www.your-domain.com, and confirm that the webpage opens correctly.
Troubleshooting
If the webpage fails to open, the possible causes are as follows:
1. First, perform the steps in 1. Verify the DNS record. After you confirm that the resolution is successful, proceed with the following checks.
2. Confirm that the service can be accessed using the IP address. If not, the service may not be running.
3. Check if the browser uses HTTPS to access the website by default. Access the website using a URL that includes the HTTP protocol, such as http://www.your-domain.com.
4. Check if the service port is 80. If not, add the port number to the URL, such as http://www.your-domain.com:3000.
5. Check the domain name to see if it is locked or is missing an ICP filing.