Chapter 1 Dns Configuration; Dns Overview; Static Domain Name Resolution; Dynamic Domain Name Resolution - H3C S9500 Series Operation Manual

Operation Manual – DNS
H3C S9500 Series Routing Switches

Chapter 1 DNS Configuration

When configuring DNS, go to these sections for information you are interested in:

DNS Overview

Configuring Domain Name Resolution
Displaying and Maintaining DNS
DNS Configuration Example
Troubleshooting DNS Configuration
1.1 DNS Overview
Domain name system (DNS) is a distributed database used by TCP/IP applications to
translate domain names into corresponding IP addresses. With DNS, you can use
easy-to-remember domain names in some applications and let the DNS server
translate them into correct IP addresses.
There are two types of DNS services, static and dynamic. Each time the DNS server
receives a name query it checks its static DNS database before looking up the dynamic
DNS database. Reduction of the searching time in the dynamic DNS database would
increase efficiency. Some frequently used addresses can be put in the static DNS
database.

1.1.1 Static Domain Name Resolution

The static domain name resolution means setting up mappings between domain
names and IP addresses. IP addresses of the corresponding domain names can be
found in the static DNS database when you use applications such as telnet.

1.1.2 Dynamic Domain Name Resolution

I. Resolving procedure
Dynamic domain name resolution is implemented by querying the DNS server. The
resolution procedure is as follows:
1) A user program sends a name query to the resolver in the DNS client.
2) The DNS resolver looks up the local domain name cache for a match. If a match is
found, it sends the corresponding IP address back. If not, it sends a query to the
DNS server.
3) The DNS server looks up the corresponding IP address of the domain name in its
DNS database. 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.
1-1
Chapter 1 DNS Configuration