1. What can I do if the DNS settings do not take effect?
If the IP address resolved from a domain name is different from the IP address specified in the Domain Name System (DNS) settings of the domain name in Alibaba Cloud DNS or the DNS server that receives a DNS query cannot find the IP address corresponding to the domain name, troubleshoot the issue by following the instructions in Check whether the DNS records take effect.
2. Why is my website inaccessible, although the DNS settings have taken effect?
Configuring DNS settings is only one step in building a website. You must complete other steps before the website becomes accessible. If the website is inaccessible, first check whether the DNS settings take effect. For more information, see Check whether the DNS records take effect. If the DNS settings have taken effect but the website is still inaccessible, you can troubleshoot the issue from other aspects, such as server configurations, website programs, and network conditions.
3. What can I do if the DNS settings do not take effect within a long period of time?
In most cases, the DNS settings do not take effect because the caches on local DNS servers are not refreshed. Alibaba Cloud DNS has no control over local DNS servers. The time when the cache of a local DNS server is refreshed depends on the time-to-live (TTL) period that you specify. For more information, see FAQ about the time when DNS settings take effect.
4. Why does a ping operation fail, although the DNS settings have taken effect?
If DNS resolution is working properly, the main cause of a ping operation failure is poor network conditions. If your website is hosted on an Alibaba Cloud instance, you can submit a ticket to contact Alibaba Cloud technical support. If your website is hosted on a server provided by a third-party cloud service provider, you can contact their technical support.
5. Why are the updates to the DNS settings unable to take effect on a local DNS server?
Alibaba Cloud DNS has no control over local DNS servers. The time when the cache of a local DNS server is refreshed depends on the TTL period that you specify. We recommend that you wait until the TTL period expires.
6. How do I check whether the DNS settings take effect?
You can compare the DNS resolution results returned by the local DNS server and the authoritative DNS server with the IP address specified in the DNS settings of the domain name. If the DNS resolution results returned by the local DNS server and the authoritative DNS server are the same as the IP address specified in the DNS settings of the domain name, the DNS settings take effect. If the DNS resolution result returned by the local DNS server is different from the IP address specified in the DNS settings, the main cause is that the cache of the local DNS server has not expired. We recommend that you wait 10 minutes. If the DNS resolution result returned by the authoritative DNS server is different from the IP address specified in the DNS settings, we recommend that you contact Alibaba Cloud technical support. For more information, see Check whether the DNS records take effect.
7. Can Alibaba Cloud DNS engineers contact Internet service providers (ISPs) to refresh the caches of local DNS servers?
No, we cannot help you contact ISPs to refresh the caches of local DNS servers. Visitors of a domain name are from all over the world. Each local DNS server caches DNS resolution results. Alibaba Cloud DNS servers are authoritative DNS servers, and Alibaba Cloud DNS has no control over local DNS servers.
8. Can Alibaba Cloud DNS engineers unlock a domain name that is in the serverHold or clientHold state?
No, we cannot unlock a domain name that is in the serverHold or clientHold state. Only a domain name registrar or registry can lock or unlock a domain name. After a domain name is locked, the DNS settings of the domain name do not take effect. If your domain name is in the clientHold or serverHold state, contact the registrar or registry to troubleshoot the issue.
9. Can Alibaba Cloud DNS engineers help resume DNS resolution after an expired domain name is renewed?
No, we cannot help you resume DNS resolution. After a domain name expires, the domain name registrar stops the DNS services on the DNS servers of the domain name. Although Alibaba Cloud DNS provides DNS resolution, DNS recursive queries cannot be forwarded to Alibaba Cloud DNS. Alibaba Cloud DNS cannot resolve the DNS resolution issues caused by expired domain names. In most cases, DNS resolution can be resumed 24 to 48 hours after you renew an expired domain name.
10. Why are the updates to the DNS settings unable to take effect in some regions?
The updates to the DNS settings do not take effect in some regions due to the following reasons:
The caches of local DNS servers are not refreshed. The time when the updates to the DNS settings take effect depends on the intervals at which the caches of local DNS servers are refreshed. The intervals vary with regions. If the caches of local DNS servers in some regions are refreshed at longer intervals, the cached information is retained for a longer period of time and the updates to the DNS settings are unable to take effect in these regions.
DNS Request Source is not properly set. You must select Default for DNS Request Source.
11. Why does a ping operation fail to resolve a domain name to an IP address?
The ping operation fails for several reasons. The ping operation is not a proper method for troubleshooting a DNS resolution issue. For more information, see Check whether the DNS records take effect.
12. Why is my website intermittently unavailable?
The intermittent unavailability of a website may be caused by unstable loading of the website, slow loading of the website, or unstable DNS resolution.
If the intermittent unavailability is caused by unstable or slow loading of the website, the issue cannot be resolved by Alibaba Cloud DNS. DNS resolution is performed to resolve a domain name to the IP address of the server where the website is hosted. If you can open the website by using the domain name, DNS resolution is working. You can troubleshoot the issue from other aspects, such as server configurations, website programs, and network conditions.
Another possible cause is unstable DNS resolution. To resolve a domain name, a client sends a DNS query to a local DNS server first. If the local DNS server has not cached the corresponding DNS resolution result or the cache has expired, the local DNS server sequentially forwards the query to the root DNS server, the top-level DNS server, and Alibaba Cloud DNS server that is the authoritative DNS server. If the local DNS server is unstable, DNS resolution may fail. The next time DNS resolution becomes unstable, you can take a snapshot of the query result returned by the diagnostic tool provided by Alibaba Cloud and submit a ticket to Alibaba Cloud technical support.