Secondary DNS

Secondary DNS is a redundancy setup where an additional authoritative nameserver holds a copy of the zone and answers queries alongside the primary. Traditionally the secondary pulls the zone from the primary using AXFR or IXFR after a NOTIFY message or when the SOA serial increases.

Why it matters

A single DNS provider is a single point of failure for everything tied to your domain. Large outages at DNS hosts have taken many well-known sites offline at once. Adding an independent secondary on a different network lowers that risk. Multi-provider setups can also use APIs or tooling to push the same records to both, because some managed providers do not support standard zone transfers or proprietary features like ALIAS records.

Example

Delegation across two independent providers:

example.com. NS ns1.provider-a.net.
example.com. NS ns2.provider-a.net.
example.com. NS ns1.provider-b.org.
example.com. NS ns2.provider-b.org.

Resolvers pick among all four, so the loss of one provider still leaves two answering.

Common mistakes

• Choosing nameservers that share the same network or provider.
• Using proprietary record types that the second provider cannot replicate.
• Failing to monitor both sets for drift and stale serial numbers.

Related

• DNS zone transfer
• DNS provider
• Redundancy
• Authoritative nameserver

यह पेज सामान्य जानकारी है, जिसे हमारी संपादकीय टीम ने लिखा है और दस्तावेज़ीकरण बदलने पर अपडेट किया जाता है। सर्वर और प्रदाता अलग-अलग होते हैं, इसलिए बदलाव पहले सुरक्षित तरीके से जाँचें। देखें: संपादकीय नीति और अस्वीकरण.