Comcast DNS servers are dropping constantly (75.75.75.75 and 75.75.76.76) ... Revisited 2020

I agree with @EG , it's probably not an actual DNS issue. You can change the DNS servers pretty easily to verify:

Google DNS

Preferred: 8.8.8.8
Alternate: 8.8.4.4

OpenDNS

Preferred: 208.67.222.222
Alternate: 208.67.220.220

It sounds like you are enough of a geek to do this:

- Buy a Raspberry Pi, take your pick from a $10 single core Zero W all the way to a $40-$50 quad core 4B.    I use an old 2B.   There's more than enough horsepower in the Zero W to handle the workload.

- Add the appropriate case + power supply; expect to spend another $10-$20 here

- Add the smallest Micro SD card you can find; you don't need more than a 4GB device but those are soooo hard to find these days; $10? Maybe a little more.

- Get the appropriate HDMI cable.   The Zero W uses a micro HDMI whereas the larger Pi uses a standard HDMI cable.

- Find an old USB keyboard/mouse to use for the initial configuration; $10 otherwise

- Install Debian

- Configure a caching name server using well known name servers like 8.8.8.8 for the forwarders

- Disable the DHCP server on your router.   It still needs to be a DHCP client to route properly but you do not care if it never, ever, gets a response from Comcast DNS servers again and you certainly do not want it to tell your systems to use 75.75.75.75 and 75.75.76.76 for name servers.   

- Enable the DHCP server on your new system.  Tell your clients about the correct router and perhaps ntp servers, and tell them to use your new system for name resolution.

Total cost?  $20-$100.   The fact that you never have DNS problems again?   Priceless.  🙂

@person00001 

The commentary from the above poster is assuming that it is indeed a DNS problem..

Please post the requested info.

I don't often check my Xfinity e-mail inbox, and since that is the only place Xfinity was sending any communications other than billing stuff, I just got the response notifications (yes, I finally found the "forward e-mail" setting).  My follow-up is primarily for the Xfinity official response but also serves a general response.

I believe I was wrong about it being a DNS issue. It probably was a connection issue.  The responses got me thinking about my smartphone, which I had not paid enough attention to with respect to this issue.  I seem to recall that, even with the VPN active and linked to the internet through WiFi and to a different server, it also lost name resolution, which it shouldn't have done if it was solely with the Xfinity DNS server(s).  For all I know, the server to which we customers connect and the DNS server may be the same machine at Xfinity.  You guys know the Xfinity IT infrastructure, I sure don't.  Of course *technically* if there is no connection to the internet then there is probably also no DNS server either, at least as far as those downstream are concerned, but that's neither here nor there.

For what it's worth, my intention was to convey an appropriate level uncertainty in my post, but needless to say I was becoming very frustrated with my internet randomly becoming unusable.  I do tend to feel it necessary to make assumptions when I spend half an hour talking to Xfinity support with no progress towards resolution and there is no outage indication per the Xfinity web site so I am left feeling completely helpless. More than anything I wanted to put this out there in case others were experiencing a similar issue, as it appeared to be remarkably similar to the previous forum post which I reference in mine, and the similarities to the existing post were the two DNS server IP addresses.

However, reconsidering my post, I believe that I was trying to be too specific. The far more relevant question was whether the issue was on my side or Xfinity's. If the issue occurs again, I will attempt additional tests to determine if the issue is on my end, taking the suggestions presented here into account. All I really I need to do is determine with reasonable confidence whether the issue appears to be on my side or Xfinity's. If it appears to be on Xfinity's side then Xfinity would diagnose the cause of the issue, not me. I hope that I did not offend any in attempting to identify a cause so specifically with limited information.

Incidentally, apparently the same behavior occurred this past week on Wednesday, March 4, a bit after 2pm Eastern time. This time the Xfinity website did indicate an outage for my area. There was no visit to my property or service truck in the area, visible to me. I have not made any changes on my end whatsoever. It may have been a completely different cause, but I can't help but wonder.

P.S: Please reconsider using the wording, "sounds like you are enough of a geek".  For one thing, not everybody who is technically-minded appreciates being called "geek", or "nerd" for that matter, whether it is intended positively or negatively, and for another thing, it sounds a bit patronizing, as if you are talking down to someone that you consider less intelligent.

P.P.S: If the EG responses are not the official Xfinity responses, please disregard this part.  If they are, it could have sounded a bit more like the issue might have actually been on Xfinity's end and therefore a little more concilliatory, and not so much like debunking my attempt at identifying a cause. I know that technically-inclined people including myself tend to focus on thinking about the problem/solution at the expense of the interpersonal aspect, so I don't fault anyone for it as a person.

My responses are my own. I am not a CC employee. That said, I had asked you to post that requested information in order to help determine the state of your connection quality / if the RF signal stats are in or out of spec, or are marginal. FWIW, you still haven't posted them.

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@EG wrote:

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@cxrider wrote:

 There are, however, a few select individuals that appear to have the ability to escalate a thread to Comcast's attention but it seems that rarely happens.   

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That must be your opinion.. How long have you been here.. It's not as rare as you say..

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It may be my opinion.

You can check my profile and see how long I've been here and to which threads I've posted.   You can not tell how many threads I've read as I can not tell how many threads are read by official employees.    For sake of discussion, let's assume I've read 100 threads and in those 100 threads I counted three responses with respondants identified by a name 'ComcastXXXX Official Employee' and a footer also indicating they are an official employee.   I assume they are indeed an employee and responding as an employee.   If I count three threads out of 100 receiving official responses, I'm not going to call it anything but rare.   Even if my thread read count is 1/2 that and only 50 threads, that's a six percent response rate and I would still call it rare.   Maybe they do read 100% of everything posted here but if they respond less than 10% of the time what's the point?    It *appears* as if official Comcast employees are not actively involved with this forum and from a customer perspective, perception is reality.  

FWIW, I have no reason to believe that representatives of Comcast routinely read this forum.     If you read through the posts you will see very few responses from anyone identified as a Comcast employee.   There are, however, a few select individuals that appear to have the ability to escalate a thread to Comcast's attention but it seems that rarely happens.   

That being said, check your signal levels and check your error counters on the modem.   In the few months I've been following this forum I have observed that most problems are related to poor signal quality to/from the modem.    I do not know why name resolution (DNS) is more sensitive to signal quality but that seems to be the case, or at least that seems to be the first item people report as a problem with their connection.

Good luck!

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@cxrider wrote:

 There are, however, a few select individuals that appear to have the ability to escalate a thread to Comcast's attention but it seems that rarely happens.   

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That must be your opinion.. How long have you been here.. It's not as rare as you say..

I wasn't talking about employees.... I quoted this comment of yours;

"There are, however, a few select individuals that appear to have the ability to escalate a thread to Comcast's attention but it seems that rarely happens."

Look EG,

I'm not trying to knock you.   AFAIK, you are the only person that does escalate threads to Comcast; I won't assume that you are the only person that has this ability, though off the top of my head, I can not recall seeing it done by anyone else.   

Perhaps it is the case that threads get escalated and removed from this forum and that's why I do not see them.   I do not read all threads nor do I spend all day on the forum.   I will pop in from time to time, scan things, maybe chime in on a thread if I think I can help someone.   I do not read other topics such as TV, Phone, Apps, etc., I stick to Home Network.  Maybe it is the case that 50% of all posts on say TV get escalated to Comcast employees, I don't know.    I try to form data driven opinions but I'll admit, I do not actually count each and every time a thread is answered by a Comcast employee or a thread is escalated to Comcast employees.    Like everyone else, I do form impressions based on what I see so I will stick by the qualification of rarely.   To be fair, most of the problems posted here are solved without escalation and IMO, that is due in large part to your work.  I will freely admit that I'm wrong about my impressions if there's data to back up that I am wrong and that I had access the same data so I could have formed a better impression.   

Back to that particular poster.   Are you telling me that the poster's issue would have been escalated to a Comcast employee based solely on that post, without first having gone through at least checking signal quality and counters?    I will truly be surprised if that is the case. 

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@cxrider wrote:

 Are you telling me that the poster's issue would have been escalated to a Comcast employee based solely on that post, without first having gone through at least checking signal quality and counters?    I will truly be surprised if that is the case. 

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I've said, nor inferred nothing of the sort..........

I've been experiencing outages for the last 2-3 weeks and it's really annoying with 3 of us trying to work from home.  It sounds like a cable problem, but I'm beginning to doubt that.  I've noticed that I can still ping the gateway and 75.75.75.75, but DNS queries fail.  So I've switch my router config to Google's DNS servers.

@nealzilla 

Please create a new topic of your own here on this board detailing your issue. Thanks.  Year old dead now being closed.