DES-3326S Layer 3 Fast Ethernet Switch User’s Guide

entire name translation, or simply return the address of the next DNS server if the server receiving the query cannot resolve the name.

When a DNS server receives a query, it checks to see if the name is in its subdomain. If it is, the server translates the name and appends the answer to the query, and sends it back to the client. If the DNS server cannot translate the name, it determines what type of name resolution the client requested. A complete translation is called recursive resolution and requires the server to contact other DNS servers until the name is resolved. Iterative resolution specifies that if the DNS server cannot supply an answer, it returns the address of the next DNS server the client should contact.

Each client must be able to contact at least one DNS server, and each DNS server must be able to contact at least one root server.

The address of the machine that supplies domain name service is often supplied by a DCHP or BOOTP server, or can be entered manually and configured into the operating system at startup.

DHCP Servers

The Dynamic Host Configuration Protocol (DHCP) is used to dynamically assign a TCP/IP network configuration to network devices and computers on the network. It also ensures that IP address conflicts do not occur.

IP addresses are assigned from a pool of free addresses. Each IP address assigned has a ‘lease’ and a ‘lease expiration period’. The lease must be periodically renewed. If the lease is expires, the IP address is returned to the pool of available IP addresses.

106

Switch Management and Operating Concepts

Page 106
Image 106
D-Link DES-3326S manual Dhcp Servers, 106