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.
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. |
