A DNS, Domain Name System, is primarily used to map between host names and IP addresses. A host name can be a simple name, like solaris freebsd, or a fully qualified domain name (FQDN), like google.com.
FQDN
FQDN, an abbreviation of Fully Qualified Domain Name is also known as absolute name. An FQDN must end with a trailing period, which tells the resolver this name is fully qualified and it doesn't need to search its list of possible domains.
Resource Records (RR)
Resource Records are the entries in the DNS. There are several types of Resource Records, such as :
A - An A record maps a host name into a 32 bit IPv4 address.
AAAA - A quad A (AAAA) record maps a host name into a 128 bit IPv6 address. It is known as quad A because it is 4 times larger than a 32 bit address.
PTR - A Pointer Record maps IP addresses into host names.
MX - An MX record specifies a host to act as a mail exchanger for the specified host. When multiple MX records exist, they are used in order of preference, starting with the smallest value.
CNAME - It stands for Canonical Name. A common use is to assign CNAME records for common services such as FTP. When people use these service names instead of the actual host names, it is transparent when a service is moved to another host.
Friday, 23 September 2016
