Custom name servers let you run your own DNS infrastructure under your own domain. Common questions about creating and managing custom name servers in Alibaba Cloud are answered here.
What is a custom name server?
A custom name server is a self-managed DNS server that uses your own domain name for its hostname—for example, ns1.yourdomain.com instead of a third-party provider's name servers. Anyone doing a WHOIS lookup sees your branding rather than your hosting provider's.
This setup is most useful for hosting resellers and managed service providers. When you need to move infrastructure, update the IP address behind your name server once, and all domains pointing to it pick up the change automatically—no need to contact each customer individually.
Setting up custom name servers requires DNS administration experience. If you do not manage your own DNS infrastructure, use the DNS service provided by your DNS service provider instead.
What is a custom DNS host?
In the Alibaba Cloud Management Console, custom DNS host is the UI term for a glue record. It is not a server that Alibaba Cloud provides; it is a record you register at the domain registry that maps your name server hostname to its IP address.
Glue records resolve a circular dependency: if your name servers are ns1.example.com and ns2.example.com, a DNS resolver cannot look up those hostnames without first knowing which name servers are authoritative for example.com, which creates an infinite loop. The registry stores glue records directly so resolvers can bootstrap the lookup without entering that loop.
How is a glue record represented in a zone file?
A glue record pairs NS records (which delegate authority) with A or AAAA records (which provide the IP addresses for those name servers). In a zone file, it looks like this:
@ IN NS dns1.example.com.
@ IN NS dns2.example.com.
dns1.example.com. IN A 192.168.1.1
dns2.example.com. IN A 192.168.2.1What are the naming conventions for a DNS server?
Use a fully qualified subdomain as the server name, such as dns1.example.com or dns2.example.com.
Fourth-level domain names (for example, dns1.sub.example.cn) are not supported when using a .cn domain name as the DNS server name.
How many DNS servers can I create?
Up to 13 DNS servers are supported. The exact limit depends on the domain name registry for your domain's top-level domain (TLD).
Do custom DNS servers support IPv6 addresses?
Yes, custom DNS servers support IPv6 addresses.
How many IP addresses can I configure for a DNS server?
Each DNS server supports 1 to 13 IP addresses. The exact maximum is determined by the domain name registry for your domain's TLD.
A .cn domain name supports up to six custom DNS servers.
Can I change or delete a server name?
Yes, but plan carefully before making changes. Changing or deleting a server name affects every domain that relies on it. After renaming, update all DNS records that reference the old name and restart any dependent services. DNS changes can take up to 48 hours to propagate globally, so prepare a rollback strategy in advance to minimize service interruptions.
Can I change or delete the IP addresses of a DNS server?
Yes. Add, update, or remove IP addresses at any time, but at least one IP address must remain configured.
Does a custom DNS server take effect immediately after it is created?
No. After creation, DNS propagation takes time. Changes typically take several minutes to propagate within Alibaba Cloud, but global propagation can take up to 48 hours depending on TTL settings and resolver caches.
Can I delete a custom DNS server after it is created?
Yes. If the deletion fails, contact technical support on the Smart Online page.