Sometimes websites hanging, suspect DNS issues

Product Discussion Pepwave MAX
#1

I’m having a problem where about 2 times out of 10, popular website requests fail and just hang without loading (ie. www.ebay.com, www.speedtest.net). Sometimes they work great and other times just hang. This happens from multiple computers on the network so I know it is not a computer specific issue.

I suspect the Verizon DNS server is at fault and sometimes failing to resolve the URL. So I am trying to use different DNS servers rather than the automatic ones that Verizon assigns. I’m confused about the difference between the “DHCP Server > DNS Servers” and the “WAN Connection Settings > DNS Servers”. Please see the two images for the different areas. I’m trying to set it up so my DNS uses Google DNS (8.8.8.8, 8.8.4.4) rather than Verizon’s (198.224.xxx.xxx, 198.224.xxx.xxx)

QUESTIONS:

  1. What is the difference in the DHCP and WAN areas for setting DNS?
  2. What happens when I select “WAN > DNS Servers > Obtain Automatically” AND also specify to “Use the following” DNS servers?
  3. The image shows all four DNS servers, 2 for Verizon, and 2 for Google which I set. In what order are these used by the system?

Your expertise is appreciated.

image
image989×421 23.6 KB

image
image987×596 38.5 KB

image
image1033×675 50.2 KB

#2

Hello,

On the DHCP Server config the “assign automatically” option will give out the routers own address for that interface as the DNS for the clients, unticking that option you can then specify what you want to assign to clients via DHCP.

In your example above you would be issuing 8.8.8.8 / 8.8.4.4 directly to the clients, so after that the router is not involved in where they get their DNS responses as they would be sending queries directly to the servers you specify - this should achieve the result you are after.

If however you assign the routers interface you are then using the router as a local proxy / cache for your clients, which in turn would send queries to whatever upstream DNS that it knows about, e.g. ones assigned automatically by the ISP or ones you configure yourself.

On the WAN config you have the option of accepting the DNS assigned by your ISP, specifying your own, or using all of them.

I’m fairly sure that Peplink runs a version of dnsmasq under the hood, so all those options are doing is giving the internal DNS proxy a list of potential upstream DNS recursors to send traffic to. In your case here you would untick the “obtain automatically” and only tick “use the following servers”.

The DNS Resolvers settings on the third screenshot are for specifying a preferred set of upstream resolvers that the proxy will try to use first, in your case if all it knows about is 8.8.8.8 / 8.8.4.4 because of your various WAN configs you should not need to change anything here.

2 Likes
#3

Thank you for the detailed explanation. It is very helpfu.