Which two statement about the DNS are true? (Choose two.)
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Sure, I'd be happy to explain the correct statements about DNS from the CCIE Security written exam.
The client-server architecture is based on query and response messages: This statement is true. The DNS uses a client-server architecture, where the client sends a query message to a DNS server, and the server responds with a response message containing the requested information. This query and response message model is fundamental to the DNS architecture.
Query and response messages have different formats: This statement is also true. Query and response messages have different formats in DNS. For example, the query message will have a question section that contains the name of the resource record that the client is requesting, while the response message will have an answer section that contains the requested resource record.
In the DNS message header, the QR flag set to 1 indicates a query: This statement is true. The QR flag in the DNS message header is used to indicate whether the message is a query or a response. A QR flag value of 0 indicates a query, while a value of 1 indicates a response.
In the DNS header, an Opcode value of 2 represents a client status request: This statement is false. The Opcode field in the DNS message header is used to specify the type of DNS message being sent. An Opcode value of 2 represents a server status request, not a client status request.
In the DNS header, the Rcode value is set to 0 in a query message: This statement is true. The Rcode field in the DNS message header is used to indicate the result of the DNS query or response. In a query message, the Rcode value is always set to 0.
So, the correct statements about DNS from the CCIE Security written exam are: