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DNS issues
I’ve been having ongoing issues with DNS. I’ve called in and either they don’t understand what I’m saying or don’t have any suggestions.
Name resolution will stop for me over UDP (which is standard for DNS). This is true regardless of which server I use. If I resolve via TCP, however, resolution always works.
I need to know what the issue is with DNS. It’s not a connectivity thing - pings/traceroute works fine and TCP resolution always works. But more and more frequently, DNS fails and connectivity drops as a result.
Anyone have any ideas?
Name resolution will stop for me over UDP (which is standard for DNS). This is true regardless of which server I use. If I resolve via TCP, however, resolution always works.
I need to know what the issue is with DNS. It’s not a connectivity thing - pings/traceroute works fine and TCP resolution always works. But more and more frequently, DNS fails and connectivity drops as a result.
Anyone have any ideas?
Jlavaseur
Problem Solver
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948 Messages
4 years ago
Basically you have to use what protocol works best for you, you don't specify what you are using, udp is faster then tcp, but udp don't always work
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flatlander3
Problem Solver
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1.5K Messages
4 years ago
Well, if Xfinity isn't working, and you can't change the DNS settings on your gateway to point to alternative DNS servers, run one yourself.
Bind 9 recursive forward only down and dirty, no local ACL's.
options{ directory "/var/cache/bind"; recursion yes; forwarders { 1.1.1.1; 1.0.0.1; }; forward only; }Then point your devices/clients at your server. New Bind will have the dnssec lines in the .conf file too. Then your DNS server talks to cloudflare and keeps a local cache.
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MMTanner
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7 Messages
4 years ago
But the more important question is - why is UDP not working with my Comcast connection? It has to be a router thing since it fails to any server I try.
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MMTanner
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7 Messages
4 years ago
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flatlander3
Problem Solver
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1.5K Messages
4 years ago
No method that I know of to force tcp only, and there is no option for bind to exclusively use TCP. It will use TCP for a zone transfer, maybe a notify......but I think that's it.
Perhaps @ComcastMichele can point you to a network admin?
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MMTanner
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7 Messages
4 years ago
The name resolution isn't over a VPN. I do use a VPN on my laptop for work, but this issue exists regardless of if VPN is active and actually sometimes prevents me from connecting to VPN because the name can't be resolved. The VPN for my work is a split tunnel, so resolution (since the Name Servers aren't part of my corporate IP space) doesn't traverse the VPN.
No other device in my house uses VPN and it exists on those devices as well.
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MMTanner
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7 Messages
4 years ago
I have screen recordings of resolution attempts to different servers if it will help at all. It's clear normal resolution fails everytime and TCP resolution works every time.
Something is killing UDP over my connection for DNS and I need to identify what it is. I haven't seen any setting in the FW which should be doing it and I would expect any FW setting blocking external DNS for a consumer device wouldn't be very popular.
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MMTanner
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7 Messages
4 years ago
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Jlavaseur
Problem Solver
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948 Messages
4 years ago
Just out of curiosity, are you using a vpn?
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MMTanner
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4 years ago
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CCAbbie
Problem Solver
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1.4K Messages
4 years ago
Hello, @MMTanner I am glad to hear that swapping your equipment has seemed to resolve your issue! If anything else comes up, or you notice more issues, please let us know. We are happy to help.
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