Chapter 11 - Configuring Dns Client; Overview; Dns Client Support - Avaya P580 User Manual

11

Overview

DNS Client Support

Overview
Recursive vs.
Iterative
User Guide for the Avaya P580 and P882 Multiservice Switches, v6.0
Configuring DNS Client
This chapter provides an overview of the Domain Naming System (DNS)
Client support and procedures for configuring DNS client support on the
Avaya Multiservice switch.
DNS is a distributed database of name servers which supply name-to-
address translations for DNS clients. The DNS servers collectively direct
DNS Clients to the DNS Server responsible for a Name to Address
mapping; and that Server provides the specific mapping being requested.
There are three types of DNS servers:
The root name server — Located at the top of the DNS database
tree. It contains pointers to the master name servers for each of the
top-level domains. The root name servers handle the domains such
as .COM, .EDU, .GOV, etc.
The master name server — Located in the middle of the DNS
database tree. It contains pointers to the individual name servers for
each of the subdomains within its top-level domain.
The individual name server — Located at the bottom of the DNS
database tree. It contains detailed address information for the local
hosts in the subdomain.
The goal of DNS is to resolve a fully qualified domain name (FQDN) to an
IP address. This work can either be done by the DNS server or the DNS
client. These approaches are referred to as Recursive or Iterative,
respectively.
In the Recursive approach, a client sends a query to the server. Assuming
recursion is enabled, the server then looks for resolution first locally in its
own database, then in its local cache, finally by going through the DNS tree
until it finds a server that can give an authoritative answer to the query. In
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