Please enable JavaScript.

Coggle requires JavaScript to display documents.

DNS (domain name system) (Services provided by DNS (The DNS is a…

- - - - Type=A
        
        Name is a hostname and Value is the IP address for the hostname
      - Type=NS
        
        Name is a domain and Value is the hostname of an authoritative DNS server that knows how to obtain the IP addresses for hosts in the domain.
      - Type=CNAME
        
        Value is a canonical hostname for the alias hostname Name
      - Type=MX
        
        Value is the canonical hostname of a mail server that has an alias hostname Name
  - - - 16-bit number that identifies the query
      - Flags
        
        A 1-bit query/reply flag indicates whether the message is a query (0) or a reply (1)
        
        A 1-bit authoritative flag is set in a reply message when a DNS server is an authoritative server for a queried name
        
        A 1-bit recursion-desired flag is set when a client (host or DNS server) desires that the DNS server perform recursion when it doesn’t have the record
        
        A 1-bit recursionavailable field is set in a reply if the DNS server supports recursion
      - Four number-of fields
        
        These fields indicate the number of occurrences
        of the four types of data sections that follow the header
    - - A name field that contains the name that is being queried
      - A type field that indicates the type of question being asked about
        the name
    - - This section contains the resource records
        for the name that was originally queried
    - - This section contains records of other authoritative servers
    - - This section contains other helpful records