WAN DNS and LAN DNS

[William Clark]

Hello Guys,

Could anyone please tell the difference between DNS addresses under
Setting -> LAN -> DHCP Server -> DNS Server
&
Settings -> WAN -> WAN DNS Settings?

should I change both of them?
and I have another problem with some DNSes too, e.g. DNS WATCH or Comodo Secure DNS doesn't work for me, it doesn't resolve any host name!

Thanks,
William

 

[ColinTaylor]

If you move you mouse pointer over the words (i.e. "DNS Server1") you should see a question mark. Click and you will get a pop-up explaining the option.

The WAN DNS values specify the server that the router will use for its upstream DNS (if you don't want to use your ISP's servers). The LAN DNS servers are the addresses that DHCP will give out to clients on your LAN instead of itself (which is the default).

In most cases you would not want to specify DNS servers for either of those screens.

 

[martinr]

Whilst Colin's answers are always a hard act to follow, you can get the same thing in different words from Merlin himself at:

http://www.snbforums.com/threads/only-one-dns-server-in-dhcp.9353/#post-57247

"Asuswrt has the router run as a DNS proxy (that's the short version of it). That field on the DHCP page will usually contain your router's IP (that's the default when it's left empty), which means your clients will get your router's IP as the DNS, and then the router performs all DNS lookups using the DNS obtained either from your ISP, or manually entered on the WAN page. Having this means that your router can easily act as a caching server for DNS queries for your whole LAN, which can improve performances.

So if you wanted to use custom DNS servers, you would have to enter them on the WAN page, while leaving the DNS entry on the DHCP page untouched."

 

[what2be]

I know this thread is almost a year old but I was wondering the exact same thing as the OP and when I did a search this thread came up so I thought id take the time to comment on a few of the answers.

1) If your internet provider is like mine (suddenlink) and you type a invalid URL it redirects to a suddenlink ad page that generates them money. I don't know about you, but after the $160 a month i already pay and the data caps and add-ons for every little thing like unlimited data, data plan speed, etc i would rather not give them another penny so a alternate DNS server is a great solution to this.

2) Using a program like DNS Benchmark by Steve Gibson is a great tool to find a faster DNS server to use so not only do I avoid the redirects for ad pages, I also have a faster DNS resolver.

Also, Im not positive but from what I read you don't want your client DNS address to be the same as your router gateway (typically a private address like 192.168.1.1, etc) because its one more thing the router has to process. Its better to have the client use the LAN DNS address that you specify in the LAN DNS setting, which I come up with by running the DNS Benchmark program and then using the 2 fastest nameservers from there and entering them in the WAN DNS settings in my router, but I enter the fastest DNS resolver in the second box and the slower one in the first box. Then I put the same address I used for the second DNS address in the WAN DNS settings for the LAN / DHCP / DNS setting in the router. The reason I do this is that the router (asus anyway) always adds on the gateway address as an additional DNS address after the one you specify in the LAN DNS setting which tells me (again I could be wrong) is that you would want your fastest DNS server in box 2 of the WAN DNS settings so if the first one is down the router will default to the WAN DNS server primary which is really your second fastest DNS resolver. Does that make sense?

 

[thelonelycoder]

I know this thread is almost a year old but I was wondering the exact same thing as the OP and when I did a search this thread came up so I thought id take the time to comment on a few of the answers.

1) If your internet provider is like mine (suddenlink) and you type a invalid URL it redirects to a suddenlink ad page that generates them money. I don't know about you, but after the $160 a month i already pay and the data caps and add-ons for every little thing like unlimited data, data plan speed, etc i would rather not give them another penny so a alternate DNS server is a great solution to this.

2) Using a program like DNS Benchmark by Steve Gibson is a great tool to find a faster DNS server to use so not only do I avoid the redirects for ad pages, I also have a faster DNS resolver.

Also, Im not positive but from what I read you don't want your client DNS address to be the same as your router gateway (typically a private address like 192.168.1.1, etc) because its one more thing the router has to process. Its better to have the client use the LAN DNS address that you specify in the LAN DNS setting, which I come up with by running the DNS Benchmark program and then using the 2 fastest nameservers from there and entering them in the WAN DNS settings in my router, but I enter the fastest DNS resolver in the second box and the slower one in the first box. Then I put the same address I used for the second DNS address in the WAN DNS settings for the LAN / DHCP / DNS setting in the router. The reason I do this is that the router (asus anyway) always adds on the gateway address as an additional DNS address after the one you specify in the LAN DNS setting which tells me (again I could be wrong) is that you would want your fastest DNS server in box 2 of the WAN DNS settings so if the first one is down the router will default to the WAN DNS server primary which is really your second fastest DNS resolver. Does that make sense?

Your advice is bad in so many ways that I can only warn anyone wanting to follow it to read again @ColinTaylor and @martinr's answer in this thread.
If you are still convinced you need to fill in the DNS Server fields in the LAN settings, please read these two threads first:
http://www.snbforums.com/threads/disabling-your-routers-provisioning-of-dns-services.36087/
http://www.snbforums.com/threads/rt-ac68u-dns-setup-advice-please.36299/

 

[ColinTaylor]

@what2be All of your assumptions are wrong, both about DNS servers and the way clients use them. Have a read through the posts that @thelonelycoder linked to for some more information. If you have more questions after that then please feel free to ask.

P.S. But yes, if my ISP was like yours I would begrudge every penny they make from that ad page.