Cheatsheet: Difference between revisions

= DNS =

;Record Types

A Address record Returns a 32-bit IPv4 address,

AAAA IPv6 address record

CNAME Canonical name record Alias of one name to another, DNS lookup will continue by retrying the lookup with the new name.

LOC Location record Specifies a geographical location associated with a domain 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 given authoritative name servers

PTR Pointer record Pointer to a canonical name. Unlike a CNAME, DNS processing stops and just the name is returned. The most common use is for implementing reverse

DNS lookups.

SOA Start of [a zone 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,etc

SRV Service locator Generalized service location record, used for newer protocols instead of creating protocol-specific records such as MX.

TXT Text record Originally for arbitrary human-readable text in a DNS record. Now more often carries machine-readable data, opportunistic encryption, Sender Policy

Framework, etc.

* All cached records Returns all cached records of all types known to the name server. If the name server does not have any information on the name, the request will be

forwarded on.

AXFR Authoritative Zone Transfer Transfer entire zone file from the master name server to secondary name servers.

IXFR Incremental Zone Transfer Requests a zone transfer of the given zone but only differences from a previous serial number.

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;Glue Record

* A glue record is a term for a record that's served by a DNS server that's not authoritative for the zone, to avoid a condition of impossible dependencies for a DNS zone.

* What glue records do is to allow the TLD's servers to send extra information in their response to the query for the example.com zone - to send the IP address that's configured for the name servers.

* It's not authoritative, but it's a pointer to the authoritative servers, allowing for the loop to be resolved.