DNS Conflict from Cascading Routers?

CRHamburg

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Jul 18, 2017
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I have been having a repeated problem that I hope someone with a little more brain power and experience can help with. I am not quite a newbie, but only enough knowledge to end up down a big hole! I would really appreciate any ideas! Thanks so much in advance….

I live in Germany, and have Kable Deutschland supplied cable router (Compal Broadband Network WLAN Gateway). It allows very limited control of functionality, and so does not allow any customization of DNS.

I would like to use Smart DNS Proxy to access content, so believe I need to cascade a router that allows me to change the DNS settings. So I have set up the following:

1) I have connected two DD WRT routers to the cable router as access points that provide basic WIFI coverage using the ISP’s DNS. This works without a problem;

- Cable Router – 192.168.01 DHCP on, providing IP addresses to network (network 1), no ability to change DNS settings

- Wireless router 1 (D link router, running DD WRT) – LAN/LAN wired to cable router, static ip 192.168.0.3, operating as access point, dhcp off

- Wireless router 2 (Linksys router running DD WRT) – LAN/LAN wired to cable router, static ip 192.168.0.4, operating as access point , dhcp off

2) I want to run Smart DNS Proxy by cascading another router. When I add this set up I start to have problems

- Wireless router 3 (Linksys router running DD WRT), Wired LAN/WAN to cable router, static IP of 192.168.02 assigned on WAN, DHCP on, assigning 192.168.1.** (network 2), DNS set to Smart DNS Proxy

- I use a ROKU stick on wirelessly to Wireless router 3 on the 192.168.1.** network. I can generally stream to the ROKU without a problem, DNS requests are clearly sent through Smart DNS proxy by router 3.

3) But while streaming I begin to have problems:

- I often (not always) lose connectivity to the WWW for other devices trying to connect through BOTH network 1 and network 2.

- The problem appears to be DNS related, as websites can’t find DNS information.

4) I think Network 2’s connection to the internet is creating some form of conflict while running through the Cable Router. I have tried a couple of things:

- When the 192.168.0.** network is not working, I can run a VPN on a device on that network, and it will allow access to web sites

- I have tried changing the 192.168.1.** network to other DNS (OpenDNS, Google) but have the same problem. So I think the problem is not with specific to Smart DNS Proxy.

- As soon as a unplug 192.168.0.**, the 192.168.1.** network comes back to life and connects.

- I have tried instructions to bypass “DNS highjacking” by the Cable Router by adding code to Wireless Router 3. But that did not seem to help (but may not have done it right).
 
First thing to do is test if the ISP is up to no good and intercepting DNS. Use the NSLOOKUP command from the command line. You can let it use the DNS your PC learned via dhcp or you can key in any DNS on the command line. This lets you see if you get different results from dns servers. What is much more important though is you can see the DNS server that is responding. It should give you the server name and IP...kinda hard for them to fake more than the common ones.

It depends why you are doing this. It is trivial to put entries in the host file on a pc that way you are in 100% control. That of course does not work for boxes like your roku but if you really wanted to you could easily use a junk machine as a DNS server and do your own proxy and pass some though and hard code the ones you want to other IP.
 
Bill001G,
(sorry had to change my original reply) Thanks so much for your help. I just tried the NSLOOKUP, but am not sure how to interpret the results! 1) just using the pre-set DNS from my cable router I get the result below. When I 2) set the computer's DNS to 8.8.8.8 in network settings and/or use nslookup but add 8.8.8.8 to the command line it shows the Server as 8.8.8.8, and the other info is the same. Any advice?


Ds-Mac-mini:~ xxxxx$ nslookup www.tomshardware.co.uk
Server: 2a02:8108:45c0:d10:5667:51ff:fe48:1ab9
Address: 2a02:8108:45c0:d10:5667:51ff:fe48:1ab9#53

Non-authoritative answer:
www.tomshardware.co.uk canonical name = www.tomshardware.co.uk.edgesuite.net.
www.tomshardware.co.uk.edgesuite.net canonical name = a465.f1.akamai.net.
Name: a465.f1.akamai.net
Address: 88.134.181.105
Name: a465.f1.akamai.net
Address: 88.134.181.90

When I set my computers DNS to