03-06-2021 09:43 AM
Hi All,
I have a scenario
A Cisco 2900 Router connected to Internet
A Catalyst Core Switch configured with all VLANs
Access Switches connected to End devices
Now the client machines are configured with Local DNS (the DC Address), DNS for Internet.
Now say if my DNS for Internet is down for some reason, what is the best way to change it so that it is reflected to all the client machines.
My idea is to use ip name-server on the Router and change it something like 8.8.8.8. But is there a better and an accepted way of doing it? Please provide me your valuable answers
Solved! Go to Solution.
03-06-2021 10:48 AM
Hello,
not sure I understand what you are asking...if the Google DNS server is down (which never happens anyway) or unreachable, you want to use a local DNS server ?
Are you using a DHCP server ? If so, most DHCP servers can assign primary and secondary DNS server addresses to the clients.
You could even use the Cisco router as DHCP server, and assign multiple DNS servers, which will be called in order:
ip dhcp pool LAN
network 192.168.1.0 255.255.255.0
default-router 192.168.1.1
dns-server 8.8.8.8 192.168.1.1
03-06-2021 06:01 PM
hi,
the 'ip name-server' is only for doing local DNS on the router itself, i.e. ping to google.com instead of an IP.
are you doing DHCP on the router, switch or on a separate server? i suggest adding a tertiary DNS for Internet name translation and push the policy to your client machines.
03-06-2021 10:00 AM
If the router internet fails, even google DNS not reachable, I do not see any solution here. until you have 2 different links to the Internet, in that case, your DNS still works on the route.
i suggest having a local DNS that is in your control. if you like you can use Google DNS.
03-06-2021 10:48 AM
Hello,
not sure I understand what you are asking...if the Google DNS server is down (which never happens anyway) or unreachable, you want to use a local DNS server ?
Are you using a DHCP server ? If so, most DHCP servers can assign primary and secondary DNS server addresses to the clients.
You could even use the Cisco router as DHCP server, and assign multiple DNS servers, which will be called in order:
ip dhcp pool LAN
network 192.168.1.0 255.255.255.0
default-router 192.168.1.1
dns-server 8.8.8.8 192.168.1.1
03-09-2021 05:16 AM
Thanks for the solution, Do we mention the DNS provided by the ISP on the DHCP options?
03-09-2021 06:48 AM
Hello,
that is an option. You can add the ISP provided DNS server, the DNS servers will be called in sequence.
03-09-2021 07:09 AM
Thank you for the answer
03-06-2021 06:01 PM
hi,
the 'ip name-server' is only for doing local DNS on the router itself, i.e. ping to google.com instead of an IP.
are you doing DHCP on the router, switch or on a separate server? i suggest adding a tertiary DNS for Internet name translation and push the policy to your client machines.
03-09-2021 05:18 AM
Thanks for the answer, does the ip name-server specify the DNS, so that when client traffic hits the router it uses it for name resolution?
Where do we setup the tertiary DNS? on the Windows server?
Discover and save your favorite ideas. Come back to expert answers, step-by-step guides, recent topics, and more.
New here? Get started with these tips. How to use Community New member guide