Reference Guide

460 | IPv4 Addressing
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Directed Broadcast
By default, FTOS drops directed broadcast packets destined for an interface. This default setting provides
some protection against Denial of Service (DOS) attacks.
To enable FTOS to receive directed broadcasts, use the following command in the INTERFACE mode:
To view the configuration, use the
show config command in the INTERFACE mode.
Resolution of Host Names
Domain Name Service (DNS) maps host names to IP addresses. This feature simplifies such commands as
Telnet and FTP by allowing you to enter a name instead of an IP address.
Dynamic resolution of host names is disabled by default. Unless the feature is enabled, the system resolves
only host names entered into the host table with the
ip host or ipv6 host command.
• Enable dynamic resolution of host names
• Specify local system domain and a list of domains
• DNS with traceroute
Enable dynamic resolution of host names
By default, dynamic resolution of host names (DNS) is disabled.
To enable DNS, use the following commands in the CONFIGURATION mode:
Command Syntax Command Mode Purpose
ip directed-broadcast
INTERFACE Enable directed broadcast.
Command Syntax Command Mode Purpose
ip domain-lookup
CONFIGURATION Enable dynamic resolution of host names.
ip name-server ipv4-address
[ipv4-address2 ... ipv4-address6]
ipv6 name-server ipv6-address
[ipv6-address2 ... ipv6-address6]
CONFIGURATION Specify up to 6 IPv4 or IPv6 name servers. The order you
entered the servers determines the order of their use. You
may have IPv4 and IPv6 name servers configured at the
same time.