DNS Focus

A duplicate of a primary zone on another server that contains a backup copy of the primary master zone database file, stored as an identical text file on the server's local drive

Secondary zone

Creates an alias that points to the canonical name (i.e., the "real" name) of a host identified by an A record. Used to provide alternative names by which systems can be identified

CNAME

Provides a name-to-address mapping that supplies an IPv6 address for a specific DNS name. This record type performs the primary function of the DNS, converting names to addresses

AAAA

occurs when a DNS server retains information about names that do not exist in a domain

Negative caching

Contains the master copy of the zone database, where administrators make all changes to the zone's resource records

Primary zone

The DNS server receiving the name resolution request takes full responsibility for resolving the name. If the server possesses information about the requested name, it replies immediately to the requester. (type of query)

Recursive query

when a computer needs to convert an IP address into a DNS name

Reverse name resolution

The process by which one DNS server sends a name resolution request to another DNS server is called a

referral

a client program that generates DNS queries and sends them to a DNS server for fulfillment

resolver

what are the highest-level DNS servers in the entire namespace

root name servers

Provides a name-to-address mapping that supplies an IPv4 address for a specific DNS name. This record type performs the primary function of the DNS, converting names to addresses

A

The server that receives the name resolution request immediately responds with the best information it possesses at the time. This information could be cached or authoritative, and it could be a resource record containing a fully resolved name or a reference to another DNS server. DNS servers use iterative queries when communicating with each other

Iterative query

Identifies a system that will direct e-mail traffic sent to an address in the domain to the individual recipient, a mail gateway, or another mail server

Mail exchanger (MX)

Identifies a DNS server functioning as an authority for the zone. Each DNS server in the zone (whether primary master or secondary) must be represented by a ______ record

Name server (NS)

Provides an address-to-name mapping that supplies a DNS name for a specific address in the in-addr.arpa domain. This is the functional opposite of an A record, used for reverse lookups only

Pointer (PTR)

Indicates that the server is the best authoritative source for data concerning the zone.

Start of Authority (SOA)

A copy of a primary zone that contains the key resource records that identify the authoritative servers for the zone.

Stub zone

DNS consists of three elements

The DNS name space, Name servers, Resolvers

The amount of time that DNS data remains cached on a server is called

Time To Live (TTL)

generic top-level domains (gTLDs), 6

com, edu, gov, mil, net, org

country-code top-level domains (ccTLDs) 4

fr, de, us, ca

an administrative entity you create on a DNS server to represent a discrete portion of the DNS namespace

zone