What are the various fields of DNS message format?

What are the various fields of DNS message format?

DNS has two types of messages: query and response. Both types have the same format. The query message consists of a header and question records; the response message consists of a header, question records, answer records, authoritative records, and additional records (see Figure4).

What is DNS explain the DNS message format?

DNS message format The DNS protocol uses two types of DNS messages, queries and replies; both have the same format. Each message consists of a header and four sections: question, answer, authority, and an additional space. A header field (flags) controls the content of these four sections.

What are the two different types of DNS requests?

What are the two types of DNS requests? What do they each do? Recursive Query – Query that demands a resolution or the answer that it can’t be found. Iterative Query – Query that does not demand a resolution.

What is DNS query message?

A DNS Query is a request for information sent from a DNS Client to a DNS Server. A DNS Query message from the DNS Client contains mainly below information. 1) Fully Qualified Domain Name (FQDN): Fully Qualified Domain Name (FQDN) of the resource the client is trying to resolve.

What are the three domains of DNS?

The domain name space is divided into three different sections: generic domains, country domains, and inverse domain.

What is DNS primary and secondary?

Primary DNS servers contain all relevant resource records and handle DNS queries for a domain. By contrast, secondary DNS servers contain zone file copies that are read-only, meaning they cannot be modified.

What are the three main components of DNS?

The DNS has three components: authoritative servers, recursive servers and clients (resolvers). A client (resolver) is installed in any computer with TCP/IP software. A client is any computer with Internet access capability.

What are the two types of DNS messages?

DNS has two types of messages: query and response. Both types have the same format. The query message consists of a header and the question records; the response message consisits of a header, question records, answer records, authoritative records, and additional records.

How is the header format used in DNS messages?

The format of the Header section used in all DNS messages is described in detail in Table 169 and shown in Figure 248. Where fields are used differently by the client and server in an exchange, I have mentioned in the table how the use is differentiated between the two.

What does Rd mean in DNS message format?

RD (recursion desired): This is a 1-bit subfield. When it is set (value of 1) it means the client desires a recursive answer. It is set in the query message and repeated in the response message. f. RA (recursion available): This is a 1-bit subfield.

How is an identifier generated in a DNS response?

Identifier: A 16-bit identification field generated by the device that creates the DNS query. It is copied by the server into the response, so it can be used by that device to match that query to the corresponding reply received from a DNS server.