If a domain name is inaccessible or experiences abnormal resolution, a misconfigured DNS server is a common cause. This topic describes how to use the Alibaba Cloud DNS console to quickly check your DNS server status, identify the root cause of an issue, and restore normal domain name resolution.
DNS servers for a domain name
The DNS servers for a domain name are the public authoritative server addresses for that domain name. After you register a domain name, the domain name registrar sets default DNS servers for the domain name and synchronizes them with the Top-Level Domain (TLD) name servers. During domain name resolution, a local server queries the TLD name server to obtain the DNS server addresses of the domain name. The TLD name server returns these addresses. The local server then queries these DNS server addresses to obtain the DNS records of the domain name.
Check the DNS server addresses for a domain name
Using the console
Go to the Alibaba Cloud DNS - Authoritative Zone page.
Find the target domain name. In the DNS Server IP Address column, you can view the DNS server status. Hover over the status in the DNS Server IP Address column to view the Current NS and System-assigned NS。
Using commands
nslookup -type=ns cloud-example.net
# or
dig NS cloud-example.netThe output is similar to the following:
cloud-example.net. 3547 IN NS dns30.hichina.com.
cloud-example.net. 3547 IN NS dns29.hichina.com.Go to the domain name registrar
Go to your domain name registrar to query the currently configured DNS server addresses for your domain name. The following steps use a domain name that is registered with Alibaba Cloud as an example:
Go to the Domain Names console. In the Domain Names list, find the target domain name and click Manage in the Actions column.
In the navigation pane on the left, under DNS Server Change, click Change DNS Server to view the DNS server addresses.
Diagnose and resolve status exceptions
The system periodically runs a health check to verify that your domain name correctly points to its assigned DNS servers. The system simulates a standard DNS query flow. It queries the upstream Top-Level Domain (TLD) server for the Name Server (NS) records configured for your domain name at the registrar. It then compares these records with the authoritative DNS server addresses assigned by the system. The possible statuses are as follows:
Exception 1: DNS Information For The Domain Name Not Found
This status indicates that Alibaba Cloud DNS cannot find the DNS configuration information for the domain name.
Possible cause | Impact | Solution |
DNS servers are not configured. | The domain name cannot be resolved. | You must add the servers listed under DNS Assigned By Cloud DNS as the DNS server addresses. For more information, see Modify DNS Servers. |
If the current domain name is a subdomain, this issue may be caused by missing NS records for the primary domain name. | The domain name cannot be resolved. | You must add two NS records on the DNS server for your primary domain name to point the subdomain to the DNS servers assigned by Alibaba Cloud DNS. For more information, see Subdomain Management. Important If you receive the DNS Information For The Domain Name Not Found message after configuring the NS records for the primary domain name, there may be a synchronization delay. This occurs because the system checks DNS server status on a schedule and sends notifications asynchronously. Please wait for 5 minutes and then refresh the page. |
Exception 2: Assigned NS not used
This status indicates that the domain name is not using the DNS server addresses assigned by Alibaba Cloud DNS.
Possible cause | Impact | Solution |
The current DNS server addresses for the domain name are not Alibaba Cloud DNS addresses. |
| To use Alibaba Cloud DNS, modify the DNS servers for your domain name. Important If you have modified the DNS servers but the DNS Server IP Address field still displays the message "Assigned NS not used", this is because the DNS server status is checked periodically and notifications are sent asynchronously. This process can cause a delay in synchronization. You can wait for 5 minutes and then refresh the page to check the status again. |
The domain name uses Alibaba Cloud DNS servers, but the server version is inconsistent with the instance version assigned by Alibaba Cloud DNS. |
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Exception 3: Probe Timeout
This status indicates that the query for the domain name's DNS server information timed out.
Possible cause | Solution |
The query for the domain name's DNS server information timed out due to network issues or other intermittent reasons. | This does not affect normal domain name resolution. The status will recover after a few minutes if you refresh the page. |
Appendix
Alibaba Cloud's public authoritative server addresses
If you use Alibaba Cloud DNS for domain name resolution, Alibaba Cloud assigns different DNS server addresses to your domain name based on whether you use a paid edition or the Free Edition. The DNS server address ranges are as follows:
Public Authoritative Zone | DNS Server Address |
Paid Edition | vip(1-8).alidns.com |
Free Edition | dns(1-32).hichina.com, ns(1-8).alidns.com |
References
If you are not familiar with the classification of DNS servers and the role of authoritative DNS servers, see DNS Server Levels.
If you are not familiar with the domain name resolution process, see DNS resolution process.
Modifying the DNS servers for a domain name can cause abnormal resolution and service disruptions. To reduce the risks associated with configuration migration, see How to smoothly migrate domain name resolution to Alibaba Cloud DNS.