Cisco Cisco Email Security Appliance C160 Mode D'Emploi

In Step 3, you define the default router (gateway) and configure the DNS settings, 
and then set up the appliance to receive and or relay email by configuring the Data 
1, Data 2, and Management interfaces.

Type the IP address of the default router (gateway) on your network.

Next, configure the DNS (Domain Name Service) settings. IronPort AsyncOS 
contains a high-performance internal DNS resolver/cache that can query the 
Internet’s root servers directly, or the system can use DNS servers you specify. If 
you choose to use your own servers, you will need to supply the IP address and 
hostname of each DNS server. You can enter up to four DNS servers via the 
System Setup Wizard. Please note that DNS servers you enter will have an initial 
priority of 0. For more information, see 

The appliance requires access to a working DNS server in order to perform DNS 
lookups for incoming connections. If you cannot specify a working DNS server 
that is reachable by the appliance while you are setting up the appliance, a 
workaround is to either select “Use Internet Root DNS Servers” or to specify, 
temporarily, the IP address of the Management interface so that you can complete 
the System Setup Wizard.

Your IronPort appliance has network interfaces that are associated with the 
physical ports on the machine. For example, on C60/600/650/660, 
C30/300/350/360, and X1000/1050/1060 appliances, three physical Ethernet 
interfaces are available. On C10/100/150/160 appliances, two physical Ethernet 
interfaces are available.

To use an interface, mark the “Enable” checkbox and then specify an IP address, 
network mask, and fully qualified hostname. The IP address you enter should be 
the address intended for your inbound mail as reflected in your DNS records. 
Typically this address would have an MX record associated with it in DNS.