Cisco IE 4000, Software Configuration Manual

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Performing Switch Administration
Information About Performing Switch Administration
When multiple sources of time are available, NTP is always considered to be more authoritative. NTP time overrides the
time set by any other method.
Several manufacturers include NTP software for their host systems, and a publicly available version for systems running
UNIX and its various derivatives is also available. This software allows host systems to be time-synchronized as well.
NTP Version 4
NTP version 4 is implemented on the switch. NTPv4 is an extension of NTP version 3. NTPv4 supports both IPv4 and IPv6
and is backward-compatible with NTPv3.
NTPv4 provides these capabilities:

Support for IPv6.

Improved security compared to NTPv3. The NTPv4 protocol provides a security framework based on public key
cryptography and standard X509 certificates.

Automatic calculation of the time-distribution hierarchy for a network. Using specific multicast groups, NTPv4
automatically configures the hierarchy of the servers to achieve the best time accuracy for the lowest bandwidth
cost. This feature leverages site-local IPv6 multicast addresses.
For details about configuring NTPv4, see Cisco IOS IPv6 Configuration Guide on Cisco.com.
DNS
The DNS protocol controls the Domain Name System (DNS), a distributed database with which you can map hostnames
to IP addresses. When you configure DNS on your switch, you can substitute the hostname for the IP address with all IP
commands, such as
ping , telnet , connect , and related Telnet support operations.
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,
for example, the File Transfer Protocol (FTP) system is identified as ftp.cisco.com .
To keep track of domain names, IP has defined the concept of a domain name server, which holds a cache (or database)
of names mapped to IP addresses. To map domain names to IP addresses, you must first identify the hostnames, specify
the name server that is present on your network, and enable the DNS.
Default DNS Configuration
Login Banners
You can configure a message-of-the-day (MOTD) and a login banner. The MOTD banner displays on all connected
terminals at login and is useful for sending messages that affect all network users (such as impending system
shutdowns).
The login banner also displays on all connected terminals. It appears after the MOTD banner and before the login
prompts.
Feature Default Setting
DNS enable state Enabled.
DNS default domain name None configured.
DNS servers No name server addresses are configured.