What is the path of a recursive query?
The path of a recursive query refers to the sequence of DNS servers traversed during the resolution process of a DNS query. When a client device sends a DNS query to a resolving nameserver, the resolving nameserver follows a specific path to obtain the necessary information and provide a response to the client.
Here's a simplified overview of the path of a recursive query:
Local DNS Cache: The resolving nameserver first checks its local DNS cache to see if it already has the requested DNS information stored. If the information is found and has not expired, the resolving nameserver can directly provide the response to the client.
Root DNS Servers: If the information is not available in the local cache, the resolving nameserver queries the root DNS servers. These servers are responsible for managing the top-level domains (TLDs), such as ".com" or ".org." The resolving nameserver asks the root servers to provide the IP address of the authoritative DNS server responsible for the TLD of the requested domain.
TLD Authoritative DNS Server: The resolving nameserver receives a response from the root DNS servers containing the IP address of the authoritative DNS server for the TLD. It then queries this TLD authoritative DNS server to obtain the IP address of the authoritative DNS server responsible for the next level domain.
Authoritative DNS Server for the Domain: The resolving nameserver sends a query to the authoritative DNS server responsible for the domain name. This authoritative server holds the definitive DNS information for the requested domain. The resolving nameserver requests the IP address associated with the domain name.
Response and Caching: The authoritative DNS server responds to the resolving nameserver with the IP address of the requested domain. The resolving nameserver caches this information for a specified time (based on the TTL value) to speed up future queries. It then sends the IP address back to the client device that initiated the DNS query.
It's important to note that the actual path of a recursive query may vary based on the specific DNS infrastructure and configuration. Additionally, there might be additional layers of DNS servers involved, such as intermediate resolvers or caching servers, depending on the network setup.
The path of a recursive query ensures that the resolving nameserver follows a step-by-step process to retrieve the required DNS information from authoritative servers, ultimately providing the correct response to the client that initiated the query.