Domain Name Service (DNS) is an application layer protocol used to keep track of computers, resources and services in network environment.
It uses four servers:DNS uses TCP for replication and UDP for translation since it requires fastness.
How Does DNS Work?
Whenever an end user requests for connecting to a domain on the internet, the request is first transferred to its local DNS server. If it has the information for which user is asking for, it replies immediately and connection is established. If local DNS has no information, the request goes to ISP router to check to see if it has the desired address. The request is then transferred to Root Server, which contains all addresses of Top Level Domains. If the address of domain is still not found, it finally goes to respective TLD server. TLD server will then search for the particular requested domain in its address tables and forward the request to thr Authoritative Server (AS). AS may be any system in the network of that domain. The reverse connection process starts here. It'll respond back to the TLD server establishing connection in between TLD and AS servers. TLD server will send reply to root server giving it the information about the respective address. Root server in turn will pass on this information to ISP router which sends it to the local DNS server of end user. The end user can now get connected to desired domain.
While the address sent by AS to end user, the intermediate servers also add this address to their database and update it. In other words, it is said that this address is cached into these servers. Thus whenever next request is made to same domain, the local DNS server is capable of providing the reply to user avoiding the need to contact further servers.
Here's how I can summarize the working of DNS:
No comments:
Post a Comment