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Can Comcast's DNS server addresses of 75.75.75.75 & 75.75.76.76 be used by other ISPs?

Are other ISPs besides Comcast able to use Comcast's DNS server addresses of 75.75.75.75 & 75.75.76.76?

An organization I am working for has switched over to using Comcast fiber optics as its primary internet service provider (ISP). We also have a second internet service provider (Etheric Networks (https://ethericnetworks.com/) which provides satellite dish based internet services.

Our internet service is set up in a failover configuration using a SonicWALL TZ600 router so that if our primary Comcast fiber optic internet service fails then our internet service will automatically switch over to Etheric until the Comast fiber optic service is restored.

We would like to continue to use the static external DNS server addresses of 75.75.75.75 and 75.75.76.76 in place if our internet service ever switches over to Etheric should the Comcast fiber optic internet service become unavailable.

Our question is if our internet service switches over to using the Etheric internet service will the external IP DNS server addresses of 75.75.75.75 and 75.75.76.76 still be valid and provide timely DNS name resolution?

Or is there a different type of method we should be using to handle our internet service and DNS name resolution switch over?
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IT Guy
Asked:
IT Guy
3 Solutions
 
Tom CieslikIT EngineerCommented:
Yes, those are public DNS servers like google 8.8.8.8
You can use it with any IPS providers
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Blue Street TechLast KnightCommented:
Hi Knowledgeable,

Are other ISPs besides Comcast able to use Comcast's DNS server addresses of 75.75.75.75 & 75.75.76.76?
There have been quite a few mergers as of recent so they could be for that reason. But aside from that they technically shouldn't but you can use any Public Recursive DNS server...that is what they are there for!

Our question is if our internet service switches over to using the Etheric internet service will the external IP DNS server addresses of 75.75.75.75 and 75.75.76.76 still be valid and provide timely DNS name resolution?
Yes, again you can use any Public Recursive DNS server made available. Generally, ISP DNS servers are slower and bog compared to OpenDNS, 4-8's (google) and the like.

Or is there a different type of method we should be using to handle our internet service and DNS name resolution switch over?
I'd recommend OpenDNS servers (208.67.222.222 & 208.67.220.220) or DYN Internet Guides (216.146.35.35 & 216.146.36.36) https://dyn.com/labs/dyn-internet-guide/ for both ISPs that way when they fail-over there is no change. It is not really as important as you may think because everything should be assigned through your local DHCP & DNS servers so even if your ISP changes the DHCP hand-outs should point to the local DNS server, which would then forward to a fixed Primary & Secondary Public Recursive IP address (these will not change just because one of your ISP links goes down). So the Primary & Secondary become the fail-over mechanism of DNS.

Let me know if you have any other questions!
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masnrockCommented:
Yes you can keep using the Comcast DNA servers as they keep them publicly available. However, I would use a different set like Google (8.8.8.8) or Level 3 (4.2.2.2) to avoid being tied to Comcast's whims if they have issues.
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