DNSv4/v6 Configuration
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69. DNSv4/v6 Configuration
69.1
Introduction to DNS
DNS (Domain Name System) is a distributed database used by TCP/IP applications
to translate domain names into corresponding IPv4/IPv6 addresses. With DNS, you can
use easy-to-remember and signification domain names in some applications and let the
DNS server translate them into correct IPv4/IPv6 addresses.
There are two types of DNS services, static and dynamic, which supplement each
other in application. Each time the DNS server receives a name query it checks its static
DNS database first before looking up the dynamic DNS database. Some frequently used
addresses can be put in the static DNS database, the reduction the searching time in the
dynamic DNS database would increase efficiency. The static domain name resolution
means setting up mappings between domain names and IPv4/IPv6 addresses. IPv4/IPv6
addresses of the corresponding domain names can be found in the static DNS database
when you use some applications. Dynamic domain name resolution is implemented by
querying the DNS server. A user program sends a name query to the resolver in the DNS
client when users want to use some applications with domain name, the DNS resolver
looks up the local domain name cache for a match. If a match is found, it sends the
corresponding IPv4/IPv6 address back to the switch. If no match is found, it sends a query
to a higher DNS server. This process continues until a result, whether success or failure,
is returned.
The Domain Name System (DNS) is a hierarchical naming system for computers,
services, or any resource participating in the Internet. It associates various information
with domain names assigned to such participants. Most importantly, it translates humanly
meaningful domain names to the numerical (binary) identifiers associated with networking
equipment for the purpose of locating and addressing these devices world-wide. An often
used analogy to explain the Domain Name System is that it serves as the "phone book"
for the Internet by translating human-friendly computer hostnames into IP addresses.
The Domain Name System makes it possible to assign domain names to groups of
Internet users in a meaningful way, independent of each user's physical location. Because
of this, World-Wide Web (WWW) hyperlinks and Internet contact information can remain
consistent and constant even if the current Internet routing arrangements change or the
participant uses a mobile device. Internet domain names are easier to remember than IP
addresses such as 208.77.188.166(IPv4) or 2001:db8:1f70::999:de8:7648:6e8 (IPv6).
People take advantage of this when they recite meaningful URLs and e-mail addresses