DNS Query

Definition of DNS Query in the Network Encyclopedia.

What is DNS Query?

DNS Query is one of three methods of requesting that name servers handle name lookups. DNS queries can occur between resolvers and name servers, and between name servers and other name servers.

DNS Query
DNS Query

Queries can be answered by the queried name server from its local DNS database, from previously cached query results, or from a referral to another name server.

The three basic kinds of DNS queries are recursive queries, iterative queries, and inverse queries.

For more information on these types of DNS queries, see their respective entries in this work.

Common DNS Request Types

DNS  Lookup  Type Description Function
 A IPv4 address record Returns a 32-bit IP address, which typically maps a domain’s hostname to an IP address, but also used for DNSBLs  and storing subnet masks
 AAAA IPv6 address record Returns a 128-bit IP address that maps a domain’s hostname to an IP address
 ANY All cached records Returns all records of all types known to the name server
 CNAME Canonical name record Alias of one name to another: the DNS lookup will continue by retrying the lookup with the new name
 MX Mail exchange record Maps a domain name to a list of message transfer agents for that domain
 NS Name server record Delegates a DNS zone to use the specified authoritative name servers
 PTR Pointer record Pointer to a canonical name that returns the name only and is used for implementing reverse DNS lookups
 SIG Signature Signature record
 SOA Start of authority  record Specifies authoritative information about a DNS zone, including the primary name server, the email of the domain  administrator, the domain serial number, and several timers relating to refreshing the zone
 SRV Service locator Generalized service location record, used for newer protocols instead of creating protocol-specific records such as MX
 TXT Text record Carries extra data, sometimes human-readable, most of the time machine-readable such as opportunistic encryption,  DomainKeys, DNS-SD, etc.

See also:


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