====== Recursive Resolver vs Authoritative DNS Server ======

DNS involves two fundamentally different types of servers:

  * **Recursive Resolvers**
  * **Authoritative DNS Servers**

Although both answer DNS queries, they perform very different roles.

-----

===== Recursive Resolver =====

A recursive resolver is the DNS server that users query directly.

Examples include:

  * Google Public DNS (`8.8.8.8`)
  * Cloudflare DNS (`1.1.1.1`)
  * Quad9 (`9.9.9.9`)
  * Your ISP's DNS servers

Its responsibilities are:

  * Receive DNS queries from users.
  * Search its cache.
  * Perform recursive lookups if necessary.
  * Cache the results according to TTL.
  * Return the final answer to the client.

<code>
User
   │
   ▼
Recursive Resolver
</code>

-----

===== Authoritative DNS Server =====

An authoritative server stores the official DNS records for a domain.

Example:

<code>
example.com
      │
      ▼
ns1.example.com
</code>

It does **not** perform recursive lookups.

Instead, it simply answers questions about domains for which it is authoritative.

Typical records include:

  * A
  * AAAA
  * MX
  * TXT
  * NS
  * SOA
  * CAA

-----

===== Query Flow =====

Suppose a user requests:

<code>
www.example.com
</code>

The lookup proceeds as follows:

<code>
Browser
   │
   ▼
Recursive Resolver
   │
   ▼
Root Server
   │
   ▼
TLD Server
   │
   ▼
Authoritative Server
   │
   ▼
Answer
</code>

The browser communicates only with the recursive resolver.

-----

===== Comparison =====

^ Recursive Resolver ^ Authoritative Server ^
| Receives queries from users | Stores official DNS records |
| Performs recursive lookups | Never performs recursion |
| Uses cache | Does not cache other domains |
| Returns cached answers | Returns authoritative answers |
| Usually operated by ISPs or public DNS providers | Usually operated by DNS hosting providers |

-----

===== Why Responses May Differ =====

Recursive resolvers may return different answers because:

  * Their cache has not expired.
  * They are located in different countries.
  * CDN or GeoDNS returns different IP addresses.
  * DNS propagation is still in progress.

Authoritative servers, however, always return the current published records.

-----

===== Can I Query the Authoritative Server Directly? =====

Yes.

For example:

<code>
dig @ns1.example.com example.com A
</code>

This bypasses recursive resolvers and asks the authoritative server directly.

This is useful for verifying that recent DNS changes have been published.

-----

===== How Telenegar DNS Check Works =====

Telenegar DNS Check queries multiple recursive DNS providers around the world.

This allows you to:

  * Compare DNS responses.
  * Detect propagation delays.
  * Observe GeoDNS behavior.
  * Compare public DNS providers.

Telenegar also supports querying authoritative DNS servers directly, allowing you to compare published records with what recursive resolvers currently return.

-----

===== Common Misconceptions =====

  * **Recursive DNS servers own the DNS records.**
    * False. They only cache and forward queries.

  * **Authoritative servers cache Internet DNS records.**
    * False. They only answer for their own zones.

  * **Google DNS is authoritative for every domain.**
    * False. Google Public DNS is only a recursive resolver.

-----

===== Related Topics =====

  * [[networking:dns:dns|DNS Explained]]
  * [[networking:dns:dns-propagation|DNS Propagation]]
  * [[networking:dns:cdn|CDN and GeoDNS]]
  * [[tools:dnscheck|DNS Check]]

-----

{{tag>dns resolver authoritative recursion nameserver}}