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Step-by-Step Configuration and Troubleshooting Best Practices for the NGFW, NGIPS and AMP Technologies A Visual Guide to the Cisco Firepower Threat Defense (FTD)
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ASA version 7.2-very urgent

Dear all

We 've 2 ISP provider.But i 've seen failover disabled in licence tab.

Lan users access internet thro one gateway.(for ex

DNS varies to ISP provider.

I configure one isp provider DNS in one pc and other pc 've other ISP provider DNS,But Gateway same to both pcs.Is it possible.

Kindly guide me


Re: ASA version 7.2-very urgent

if the dns reachable publicly through the internet then

they will go from one ISP to ISP for dns query!

Re: ASA version 7.2-very urgent

Hello Bic,

"Is it possible"

Is what possible? Failover? Simply no. Assigning different ISPs' DNS IP addresses as preferred DNS server to different computers has no sense and no use while gateway address is intact.

A workaround can be in a way where you set your DHCP server to distribute two gateways and two DNS servers. I remember a registry entry can make the computer act as a IP SLA monitor to switch between gateways, but cant remember if supported in XP.


Re: ASA version 7.2-very urgent

This would largely depend on your ISP's DNS settings. Most ISPs allow lookups (or recursive lookups) only to their clients (as in IP Addresses assigned to them). If you failover to ISPB and the clients machine has First ISP's DNS server assigned to it, this will create issues. Just assign two DNS servers to each machine, putting the primary ISP (the one mostly active) as the Primary DNS also. If it goes down Windows will automatically fallback to the second server.

You can also assign One Public DNS Server (not belonging to any of your ISPs).



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