Hi, I've been trying to get to the bottom of this for a few days but i'm no closer so i'm hoping someone out there can help.
We have an existing ASA which the rest of the LAN connects to. We then have a new Cisco 1900 router which connects to the ASA and has 2 networks 10.20.4.0/24 and 10.20.5.0/24. I have full traffic through the ASA to the existing network which is 10.20.0.0/22. From the 10.20.4.0 and 5.0 networks i can ping IP addresses in existing network and can ping Internet IP addresses. From existing network i can ping back to IP's on the 4.0 and 5.0 networks. so my router is passing traffic ok. However it doesn't appear to be passing DNS. I have my DNS servers set in existing network 10.20.0.20 and 10.20.0.21 these are included in the DHCP scope of the 2 4.0 and 5.0 pools and show when i do an ipconfig /all on the clients. I am able to ping them both OK too.
When i look at Wireshark on the DNS servers i can see that they receive the request and send a response but this response never makes it to the client. If i connect to the router using Putty and issue a ping to www.google.co.uk and source it from the 10.20.4.1 interface i do get DNS resolution but clients don't.
