Tag: Resolver

DNS Caching SEQ

Posted on by lechuck park

From Claude with some prompting
This improved diagram illustrates the DNS caching sequence more comprehensively. Here’s a breakdown of the process:

  1. A user types a URL in a browser.
  2. The system attempts to translate the domain to an IP address using DNS caches.
  3. Process Keep it: Checks the process-level DNS cache. If the information isn’t found here (“No”), it moves to the next step.
  4. OS Keep it: Checks the operating system-level DNS cache. For Linux, it uses the “nslookup -c domain” command, while for Windows, it uses “ipconfig /displaydns”. If the information isn’t found here (“No”), it proceeds to the next step.
  5. Query to the Resolver Server: The system queries the DNS resolver server. The resolver’s information is found in “/etc/resolv.conf” for Linux or the Windows Registry for Windows systems.
  6. If the resolver doesn’t have the information cached (“No”), it initiates a recursive query through the DNS hierarchy:
    • Root DNS
    • TLD (Top-Level Domain) server
    • Authoritative server
  7. Once the IP address is obtained, an HTTP request is sent to the web server.

This diagram effectively shows the hierarchical nature of DNS resolution and the fallback mechanisms at each level. It demonstrates how the system progressively moves from local caches to broader, more authoritative sources when resolving domain names to IP addresses. The addition of the DNS hierarchy (Root, TLD, Authoritative) provides a more complete picture of the entire resolution process when local caches and the initial resolver query don’t yield results.

DNS Why?

Posted on by lechuck park

From Claude with some prompting
This image is a network diagram explaining the function and importance of DNS (Domain Name System). The main points are:

  1. WWW service works with DNS on TCP/IP.
  2. DNS is responsible for mapping domains to IP addresses.
  3. All network devices on the Internet can only route to IP addresses.
  4. It’s difficult to include actual service characteristics in IP addresses (only by number).
  5. Domain addresses are easy to use and must be mapped to IP addresses.
  6. On the client side, there’s a DNS Resolver (caching).
  7. On the server side, there’s a DNS server, which includes Authoritative Server, Root Server, and TLD Server. These are managed by IANA.
  8. At the center of the diagram is the key question: “So, how does DNS-IP Mapping work?”

This diagram visually explains the working principle of DNS and its importance in the Internet. It emphasizes the crucial role DNS plays in translating user-friendly domain names into IP addresses that computers can understand.