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Webcast-Catalyst9k
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Using 2600 Router to select different DNS at different times of day

Hello all.

Stuck in a situation, and need some advice.

We use OpenDNS for our DNS services.  However, we want to use GoogleDNS at the end of the business day, and then revert back to OpenDNS the next morning, start of business day.

My thinking is to use time-range ACLs on port 53 to accomplish this.  All clients are set to acquire DNS automatically via the DHCP (our Cisco 2600 router is also acting as DHCP).

Below are chunks from the running-config (of our test router):

 

DHCP setup

ip dhcp pool DHCP
   import all
   network 192.168.25.0 255.255.255.0
   default-router 192.168.25.254
   dns-server 208.67.220.220 8.8.8.8
   lease 3

ip name-server 8.8.8.8

 

Time Range setup

time-range GoogleDNS
 periodic weekdays 16:00 to 11:59
!
time-range OpenDNS
 periodic weekdays 00:00 to 15:59
 

ACL Statements

permit udp any host 208.67.220.220 eq domain time-range OpenDNS
permit udp any host 8.8.8.8 eq domain time-range GoogleDNS
deny udp any any eq domain

 

Assign ACL to Router interface

interface FastEthernet0/1
ip access-group Permit_Deny in

 

The router has the correct clock time via the configured NTP server.

We are getting inconsistent results from our client machines, as in some machines use OpenDNS, some use GoogleDNS, etc.

Any advice/guidance to get this to work is highly appreciated.

 

 

 

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