RR

Common DNS RR types-record in the dns
RR type value 1
:text code A

RR type-address
contains ip addressess


Type2
gives details of name server
text code NS
its gives infor authorative server
the ip addres of dns is also given

RR type 5

Text code Cname or canonical name node name
it masks changes from outside users

RR type value 6

Text code SOA
Start of authority

Provides info in detail of that zone

RR type 12
PTR
pointer
Reverse domain mapping
IP address is mapped to domain name


RR type 15
MX

Mail exchange

Specifies name of device responsible for handling emails sent to the domain


RR type 16

TXT
gives additonal text of domain to be stored


------------------------------------------------------------------------

Zone transfer

updates are dont at primar dns
and the secondary dns roll back and looksup in primary

checking condition is done when serial no in primary changes
---------------------------------------------------------------------
recursive and iterative resolution
-------------------------------------------------------------