Cisco WS-C2960S-24PD-L Software Guide - Page 134

Changing IP Information Chapter 6 Configuring the System The TFTP server can be on the same or a different LAN as the switch. If it is on a different LAN, the switch must be able to access it through a relay device or a router. For more information, see the "Configuring the Relay Device" section on page 6-7. If the configuration filename is provided in the DHCP server reply, the configuration files for a switch can be spread over multiple TFTP servers. However, if the configuration filename is not provided, then the configuration files must reside on a single TFTP server. For CLI procedures, refer to the Cisco IOS Release 12.0 documentation on Cisco.com for additional information and CLI procedures. Configuring the Domain Name and the DNS Each unique IP address can have a host name associated with it. The IOS software maintains a cache of host name-to-address mappings for use by the EXEC mode connect, telnet, and ping commands, and related Telnet support operations. This cache speeds the process of converting names to addresses. IP defines a hierarchical naming scheme that allows a device to be identified by its location or domain. Domain names are pieced together with periods (.) as the delimiting characters. For example, Cisco Systems is a commercial organization that IP identifies by a com domain name, so its domain name is cisco.com. A specific device in this domain, the File Transfer Protocol (FTP) system for example, is identified as ftp.cisco.com. To keep track of domain names, IP has defined the concept of a Domain Name Server (DNS), which holds a cache (or database) of names mapped to IP addresses. To map domain names to IP addresses, you must first identify the host names and then specify a name server and enable the DNS, the Internet's global naming scheme that uniquely identifies network devices. You can specify a default domain name that the software uses to complete domain name requests. You can specify either a single domain name or a list of domain names. When you specify a domain name, any IP host name without a domain name will have that domain name appended to it before being added to the host table. If your network devices require connectivity with devices in networks for which you do not control name assignment, you can assign device names that uniquely identify your devices within the entire internetwork. The Internet's global naming scheme, the DNS, accomplishes this task. This service is enabled by default. The switch uses the DNS server to resolve the TFTP server name to a TFTP server IP address. You must configure the TFTP server name-to-IP address map on the DNS server. The TFTP server contains the configuration files for the switch. You must configure the IP addresses of the DNS servers in the lease database of the DHCP server from where the DHCP replies will retrieve them. You can enter up to two DNS server IP addresses in the lease database. The DNS server can be on the same or a different LAN as the switch. If it is on a different LAN, the switch must be able to access it through a relay device or router. For more information, see the "Configuring the Relay Device" section on page 6-7. For CLI procedures, refer to the Cisco IOS Release 12.0 documentation on Cisco.com for additional information and CLI procedures. Catalyst 2900 Series XL and Catalyst 3500 Series XL Software Configuration Guide 6-6 78-6511-08