First stage of the DNS query

The basis of DNS (Domain Name System) is just like a phone book. They keep up a registry of a directory of domain names and translate them to Internet Protocol (IP) addresses. So what happens when we make a DNS query?

We can examine the dns query in two stages. The following explanations belong to the first stage.If the dns query fails in the first stage we pass to the second stage.

1. Is there in the browser cache?

When you open Google Chrome and type www.example.com, first of all, chrome looks at it dns cache.

If you type chrome: // net-internals / # dns in the address bar, you can see and clear the current dns cache of the browser.

Browser cache

2. Is there in the hosts file of the operating system?

Sometimes the IP addresses that correspond to the name must be defined as static.In this case, the ip address is entered in the hosts file in the system.

On Windows  C: \ Windows \ System32 \ drivers \ etc \ hosts

on Linux           / etc / hosts

3. Is there in the operating system cache?

The operating system keeps domain names in the system cache according to the value typed in the domain properties (TTL), thus providing faster resolution.

To see the TTL values in the operating system cache:

c:\>ipconfig /displaydns

To delete dns cache :

C:\>ipconfig /flushdns

4.Is there in the ISP?

If the web address still not resolved, the DNS client sends a request to the first DNS server (195.175.39.49) on the preferred network card.

If there is no result of the above steps, pass to the second stage.

Be the first to comment

Leave a Reply

Your email address will not be published.


*