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Private DNS
Use Limits
Last updated: 2025-03-18 19:50:20
Use Limits
Last updated: 2025-03-18 19:50:20

Private DNS Use Limits

Currently, use of Private DNS has the following limits and restrictions:
Note:
Finance regions are only visible to group cloud users and financial users.
If you don't use Tencent Cloud's default DNS servers 183.60.83.19 and 183.60.82.98, you will be unable to use the Private DNS service. If you need to modify the DNS server, see Getting Private IP Addresses and Setting DNS.
For more scenario requirements, provide your feedback via your rep or submit a ticket.
Item
Limit
Description
Number of DNS records
100,000
Up to 100,000 DNS records can be added under each UIN account.
Number of domains
500
Up to 500 private domains can be created under each UIN account.
TTL
1 - 86400s
TTL is the retention time of a DNS record on the DNS server and can be customized. There is a cache TTL mechanism for DNS queries. The DNS queries in Private DNS are counted based on the actual origin-pull requests and billed. You need to set the local NSCD cache to reduce origin pulls.
Available regions
Beijing, Shanghai, Guangzhou, Chengdu, Chongqing, Wuhan, Jinan, Shijiazhuang, Nanjing, Hefei, Shenyang, Changsha, Zhengzhou, Xi'an, Fuzhou, Hangzhou, Hong Kong (China), Silicon Valley, Singapore, Frankfurt, Jakarta, Bangkok, Virginia, Tokyo, Seoul, Toronto, Beijing Finance, Shanghai Finance, and Shenzhen Finance
An available region is a VPC region that can be associated with a private domain.
Private domain creation
The system supports creating TLDs conforming to IANA by default. To create custom TLDs, purchase Value-Added Service – Non-Standard TLDs first.
Reference: Root Zone Database.
Total resolution requests per instance within the VPC
5,000 times/second
The maximum DNS request threshold per instance within the VPC is 5,000 times/sec (including private domain resolution and external recursive resolution). If the DNS query peak per second exceeds the threshold, a risk of speed limit will be there, and the availability SLA (99.99%) of the paid version for private domain resolution cannot be guaranteed.
Note: This instance includes both CVM and Lighthouse.
Number of External Recursive Resolution Requests per Instance within VPC
100 times/second
The threshold for external recursive resolution requests per instance within the VPC is 100 times/second. If the speed limit threshold is exceeded, a risk of speed limit will be there.
Note: This instance includes both CVM and Lighthouse.
Total external recursive resolution requests for all instances within the VPC
1,000 times/second
The overall external recursive request threshold within a single VPC is 1,000 times/second. If the speed limit threshold is exceeded, a risk of speed limit will be there.
Volume of External Recursive Resolution Requests for a Single Domain within the VPC
30 times/second
The external recursive resolution request threshold for a single domain (such as example.com) within a single VPC is 30 times/second. If the speed limit threshold is exceeded, a risk of speed limit will be there.
DNS request protocol
-
The DNS request protocol through private domain resolution within the VPC supports the UDP Protocol, and each request packet must be less than 512 bytes.
Note: This instance includes both CVM and Lighthouse.
Recursive subdomain resolution
-
After the Recursive Subdomain Resolution feature of Private DNS is enabled, queries for a subdomain for which no records are set will be forwarded to the public DNS. If this feature is not enabled, such queries cannot be properly resolved.
CNAME flattening
-
If you have set a CNAME record, the target IP of the CNAME record will be synchronously returned after the CNAME flattening feature is enabled. We recommend you enable the Recursive Subdomain Resolution feature before using this feature. Otherwise, no final result can be returned if the target IP of the CNAME record requires query in the public DNS.

Round-Robin DNS Record Limits

Note:
Number of "Round-Robin DNS Records" refers to the number of records that can be added under the same host and the same record type.
Those out of the limit cannot be properly added. To add the number of round-robin DNS records, purchase Value-Added Service Packages first.
Record Type
Number of "Round-Robin DNS Records"
Remarks
A
10
-
AAAA
10
-
TXT
20
Weight setting is unavailable for round-robin DNS of TXT records.
CNAME
5
-
MX
50
-
PTR
The PTR record does not support round-robin DNS.
-

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