DNS QUERY

DEFINITION 

A DNS query (also referred to as DNS request) It is the process of sending a demand for information from the computer of the user to the DNS server. In various situations an IP address associated to the domain name is accessed through sending of DNS request.

DNS client querying is the process (that involved a trial of reaching a domain name) of sending request to DNS server to get an IP address, related to specific domain.

When one searches for a particular domain name on the browser for example

“www.example.com”, therefore the DNS client queries the DNS server, for the server to resolve the name. A DNS Query message entails the information below.

1) Fully Qualified Domain Name (FQDN): This entails the resources the client is attempting to solve. Therefore, if the application does not provide the DNS suffix, as a result, the client will add it.

 2) Query Type: This describes the type of resource record which client is attempting to solve.

3) Class: Commonly referred to as IN (Internet) class

The Fully Qualified Domain Name (FQDN) as www.webcomkenya.com, but for IP communication, the computer needs to know the corresponding IPv4 address of www.webcomkenya.com. To resolve the Fully Qualified Domain Name (FQDN) www.webcomkenya.com to an IP address, DNS Client must send a DNS Query to the DNS Server.

HOW DNS QUERY WORKS

Step 1: After entering the URL and hitting “Enter”, the computer immediately needs to resolve the Fully Qualified Domain Name (FQDN) to an IP Address. The DNS Resolver prepares a DNS Query it will send to DNS Server IP Address, which is then configured through the TCP/IP configuration settings (which is 8.8.8.8).The DNS Server uses UDP for its operation, which is referred to as port number 53.

Step 2: DNS Server performs the name resolution steps, after receiving the DNS Query from DNS Client Therefore, it will send to the DNS client a DNS Reply back, which contains an answer to the DNS query.

Types of queries

There are basically two ways to resolving a host as well as, a domain name to an IP address. It involves using of the domain name system which comprises of a recursive query as well as a non-recursive query.

1)The Recursive query is, when a DNS client directly gets the IP address of a domain, by asking the name server system to perform the complete translation.

2)The non-Recursive query is, when a DNS client contacts the name servers, one by one, until it finds the server, containing the needed information.