When does a DNS record take effect after I add it?
A DNS record takes effect immediately after it is added.
When do the updates take effect after I delete or modify a DNS record?
The time when the updates take effect depends on the time to live (TTL) period of the DNS resolution result cached on local DNS servers. The default TTL period is 10 minutes. For example, if the TTL period is set to 10 minutes or 60 seconds, 10 minutes or 60 seconds is theoretically required for the updates to the DNS settings to take effect around the world.
When do the updates take effect after I modify the DNS server information?
The time when the updates take effect depends on the TTL period of the DNS server information cached on local DNS servers. The default TTL period is 48 hours. For example, the TTL period of the DNS server information for the top-level domain (TLD) .com is 48 hours and that for the TLD .cn is 24 hours. The TTL period varies with TLDs. Therefore, a maximum of 48 hours is theoretically required for the updates to the DNS settings to take effect around the world.
Why are the updates unable to take effect immediately after I modify, delete, or disable a DNS record?
A DNS resolution result is cached on local DNS servers. If a user visits your domain name before the DNS resolution result cached on the corresponding local DNS server expires, the local DNS server returns an IP address based on the cached DNS resolution result, rather than requesting the new DNS record from Alibaba Cloud CDN. Therefore, if you modify, delete, or disable a DNS record, the updates to the DNS settings take effect after the DNS resolution result cached on local DNS servers expires. For more information about the time when DNS settings take effect, see Basic concepts.
Why do the updates take 48 hours to take effect after I modify the DNS server information?
Local DNS servers perform recursive queries only after the cached DNS server information of a domain name expires. The default TTL period of cached DNS server information is 48 hours. Therefore, a maximum of 48 hours is required for the updates to be synchronized.
Why does a DNS record take effect immediately after it is added?
A DNS record takes effect immediately after it is added only if it is the first DNS record added for a domain name. In this case, local DNS servers do not have a resolution result in the cache. If a user visits the domain name, the corresponding local DNS server performs recursive queries until it obtains the resolution result from the authoritative name server. Then, the local DNS server returns the resolution result to the user.
Why do the updates take effect faster in some regions than in other regions after I modify or delete a DNS record?
The cache timeout period varies with local DNS servers.
A local DNS server performs recursive queries only after the cache expires. For example, User A visits a domain name in Region A where the cache of the corresponding local DNS server is about to expire, whereas User B visits the same domain name in Region B where the cache of the corresponding local DNS server just takes effect. The cache of the local DNS server in Region A expires faster. Therefore, User A obtains the new resolution result faster.
When do the updates take effect after I modify a DNS record on an Alibaba Cloud DNS server?
An Alibaba Cloud DNS server is an authoritative name server. If you modify a DNS record on an Alibaba Cloud DNS server, the updates take effect within seconds. However, the time when the updates are synchronized to local DNS servers depends on the TTL period of the DNS resolution result cached on the local DNS servers.