Routing - Cisco Small Business Pro SA 520W Administration Manual

Networking

Routing

STEP 6
Routing
Cisco SA 500 Series Security Appliances Administration Guide
the ISP. When this feature is disabled, all DHCP clients on the VLAN receive the
DNS IP addresses of the ISP.
This feature is particularly useful in Auto Rollover mode. For example, if the DNS
servers for each connection are different, then a link failure may render the DNS
servers inaccessible. However, when the DNS proxy is enabled, then clients can
make requests to the router and the router, in turn, sends those requests to the
DNS servers of the active connection. You also can enable the IGMP proxy on the
respective LAN.
Click Apply to save your settings, or click Reset to revert to the saved settings.
If needed, you can change the routing mode, configure static routing, or configure
dynamic routing on your security appliance.
• Routing, page 81
• Static Routing, page 82
• Dynamic Routing, page 83
Routing
Depending on the requirements of your ISP, you can configure the security
appliance in NAT routing mode or Classic routing mode. By default, NAT is
enabled.
Network Address Transalation (NAT) is a technique that allows several computers
on a LAN to share an Internet connection. The computers on the LAN use a private
IP address range while the WAN port on the router is configured with a single
public IP address. Along with connection sharing, NAT also hides internal IP
addresses from the computers on the Internet.
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