DNS Services using way more data than before with iOS 10?

Question

Level 1

22 points

DNS Services using way more data than before with iOS 10?

Hello,

I upgraded to iOS 10 since the GM became available.

Some days ago I noticed a spike in my data usage on my carrier's report, and I went to check on the iPhone what was causing this. To my surprise, the culprit was DNS Services. Of the 515Mb I had consumed since the last reset (I reset it the same day as my carrier, which was on Sept 13th) 466Mb were DNS Services.

On the carrier's app I see that on Sept 16th there were 490Mb consumed, vs an average of 15-20Mb per day. So I assume most of those 466Mb were made that day.

Now, 466Mb of DNS requests are something like 5 billion requests. I was without WiFi connectivity that day for a total of maybe 90 minutes. In that time I did not use the iPhone except to hear music (60 minutes walking the dog, another 30 on the car). I can't figure out how or what made those requests.

I reseted the Network settings that day, and things have gone back to "normal". Except that today I can see that there are another 20Mb of DNS requests being made since the 16th. 20Mb of DNS requests are still *a lot*.

Has anybody else noticed an increased amount of DNS requests with the iOS 10?

Now, the strange part is that everything was normal before the 16th. And I installed the GM the day it came out (which was... 1 week or so before?) and I was on the betas since weeks before. I can't remember or see anything different or special being made on the 16th. Some days before, IIRC, there were some carrier updates, but why or how that would produce such an increase in DNS requests?

I tried talking with Apple Support, but the girl whom I was talking with just told me incorrect and illogical stuff, and got offended when I asked if she knew what a DNS request was, and closed the chat session. I am guessing I wont get any help there.

iPhone 6s, iOS 10

Posted on Sep 19, 2016 10:12 AM

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Answer 1

Jul 5, 2017 4:40 PM in response to jfaughnan

I have tried using several content blockers as jfaughnan suggested, however, the problem persists. I have also performed a network settings reset, and a full reset. Same thing. Verizon tier 2 support discovered the time stamps for the large (>500mb) of data usage was at times when the iPad was not in use, connected to wifi, and connected to power charging. However, I'm not sure if this is coincidence or if anyone else has noticed the same. After the reset, my DNS Services sucked up another 3.4 gig of data in less than 24 hours. I've had to completely disable cellular data service because I can no longer trust the device.

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Answer 2

Feb 1, 2017 6:54 AM in response to jfaughnan

jfaughnan wrote:

My daughter and I both have iPhone 6 and AT&T and iOS 10.latest.

My DNS use: 684kb

Her DNS use: 148MB

Not same period but her data use for DNS is crazy. Something is broken here.

Over what time period? If it was a month that's normal. As you haven't specified, for all we know that could be over a year, which would be low. The counter never resets unless you reset it. And 148 MB is not a lot of data. This thread includes someone who used 2.5 GB in one day. That's 17 times 148 MB.

DNS usage is dependent almost exclusively on how much you use a web browser. One web page can result in dozens of DNS queries. So if she uses Safari a lot and you don't that would make a significant difference in how much DNS data the phone uses.

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Answer 3

Jun 30, 2017 3:47 PM in response to rgomez

Hi, I just wanted to bump this thread to see if anyone found a solution. My iPad Mini 4 has consumed more than 7 gigs of cellular data in the last 48 hours. Almost all of it was completely from "DNS Services" under System Services.

Interestingly some of the cellular data usage occurred while connected to a fast wifi network. I am running iOS 10.3.2 on Verizon.

Any suggestions on how to figure out what is causing this abnormal data usage?

Thanks!

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Answer 4

jfaughnan

Level 3

886 points

Jul 8, 2017 8:48 AM in response to bizringer

Some thoughts ....

1. If you have another iPhone try switching SIM cards and see if DNS usage is similar. Could borrow an older phone from a friend.

2. If DNS usage is ok with SIM switch then it's something on your phone. Back it up (I like iTunes encrypted backups so saves passwords) then wipe it and activate as a new device and create a new iCloud account for test purposes (you can't delete iCloud accounts btw). Check DNS usage.

2a. DNS usage ok, wipe again, start as new device but use your original iCloud account so get back contacts, etc. Everything else you may need to rebuild.

2b. DNS usage bad - I think it's hardware then.

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Answer 5

Jul 14, 2017 6:08 PM in response to jfaughnan

jfaughnan,

Thank you for the suggestions, they were very helpful.

I tried switching SIM cards and the problem persisted. However, after extensive troubleshooting with Applecare and Verizon, we were able to determine the problem is in fact - iCloud Documents & Data. I also followed several suggestions from Apple developer forums to fix the issue.

These were the steps which successfully resolved my issue:

1. Backup all data from iCloud Drive.

2. Delete ALL Data on iCloud Drive. (Note: Some apps will require disabling iCloud Drive access to prevent sync attempts during this process).

3. Sign out of iCloud from all devices (Mac, iPad, iPhone, etc).

4. Sign back into iCloud drive on all devices.

5. Restore documents back onto iCloud Drive and wait patiently for all devices to sync over wifi.

Sigh, what a mess. But glad it's working again now. No one at tier 2 tech support from Apple or Verizon could explain or theorize what might be the cause of excessive DNS Service use, however, I did submit feedback to apple.com/feedback. It is also interesting to note that the issue only occurred on one device, and other devices (all running 10.3.2) were unaffected.

Hope this helps someone else.

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Answer 6

rgomez Author

Level 1

22 points

Sep 19, 2016 11:13 AM in response to rgomez

Just for comparison: a friend's iPhone has the total of 6.1MB of DNS services for almost a year of usage. I'm sure values will be around that mark if anybody checks their info.

So, is there any way to track what requests were made (by which App, or what name was being resolved) so I can try to pinpoint this?

I'm in the process of restoring the iPhone, hoping that things go back to normal, but without knowing what and why this happened it's just a long shot.

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Answer 7

rgomez Author

Level 1

22 points

Sep 24, 2016 8:51 AM in response to rgomez

This is still happening. I restored the iPhone some days ago, and yesterday I installed the 10.0.2 update. After installing it, I reset the statistics and some hours later (say, 8-10) where I was with WiFi for all the time except maybe 60 mins (where I did not use the iPhone directly, just heard music or keept it in my pants) I got 13MB of DNS services of a total of 20MB of cellular usage.

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Answer 8

rgomez Author

Level 1

22 points

Sep 24, 2016 8:19 PM in response to rgomez

Just checked today after coming back from the movies, and in that period (where I did not use the iPhone) I got 10MB more of DNS requests. Something is seriously wrong, but I can't figure out what.

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Answer 9

Sep 25, 2016 4:20 PM in response to rgomez

I Have the same problem, I jus updated mi iPad and my iPhone yesterday and my iPad consumed more than 2 gb in 30 min. And my iPhone more than 624 mb In 3 hours... all that from my cellular plan and the problem is DNS Services.

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Answer 10

Sep 25, 2016 4:54 PM in response to rgomez

Do you have any open pages in Safari? Try closing all open pages. Some pages autoupdate, and each page load can require multiple DNS requests.

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Answer 11

rgomez Author

Level 1

22 points

Sep 25, 2016 5:18 PM in response to Lawrence Finch

Hello,

No, I don't usually browse the web on the iPhone. And 466MB of DNS requests (in 90 minutes in my case!) are something like 5 billion requests... maybe the total requests made by normal usage in 10 years or so. This is a more subtle problem. Quite probably some app (or the iOS itself) has a bug that causes a loop of DNS requests. That' the only explanation.

Just for comparision: how much DNS services you have on your own usage? I venture that it will be at most .05% of the total usage of cellular data you have (the iPhones I have checked usually have around .015% or .020% of the usage). That's what would be normal. Anything above 1% I would start wondering what's going on.

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Answer 12

Sep 25, 2016 5:24 PM in response to rgomez

My DNS usage is 6.2 MB for half my billing period. There's clearly something wrong with your phone; perhaps a corrupted DNS server address. So the first thing I'd suggest is to Settings/General/Reset - Reset Network Settings. This should set all network settings back to the default, including your WiFi passwords and settings. I'd also check for a carrier settings update by going to Settings/General/About and tapping on the carrier's name. I know that Verizon and T-Mobile have issued carrier settings updates, and that T-Mobile's was necessary for the phone to work at all.

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Answer 13

rgomez Author

Level 1

22 points

Sep 25, 2016 5:26 PM in response to Gualberto_N

Hello Gualberto,

Do please contact Apple Support!!! (either by phone or by chat, although I think it's much better by phone) and let them know.

I spoke today with a helpful person that escalated the issue and it is now, in theory, in the Engineering Department. They will probably need logs or something similar from my iPhone, but having another case will make finding the cause of this much much easier. I'm a developer myself so I know that in cases like this, it's better to have as many cases as possible.

You might need to restore your devices from a backup, and so on (they will ask for all this before even passing your case with someone higher up) but in any case, there is no way to generate 2Gb of DNS requests with a device like this. There is clearly something very wrong that is causing that.

Let me know what happens when you contact Apple Support. It could maybe be a good idea to mention that there is another report that was already escalated of this same problem.

As a suggestion: take screenshots of the statistics every now and then (I'm usually doing so every time I will go out of a Wifi network, and when I return), that will help you present your case to Apple (I sent the ones I had).

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Answer 14

rgomez Author

Level 1

22 points

Sep 25, 2016 5:34 PM in response to Lawrence Finch

I did that the day I found this issue (on sept 16th). It did not help. Later I restored the iPhone completely, it didn't help either.

There were some carrier updates, IIRC, around the same time iOS 10 was released. This started happening 1 week later. It could certainly be the problem, and I have checked every day if there is another update, but so far nothing.

I have thought about using some of the apps that allow one to modify the DNS server used for the cellular data, but right now I will wait for Apple to contact me with the response. They said it will take them 24-48 hours to hear back from the Engineering Department.

Today I was monitoring the DNS traffic using my own firewall, but it did not show any abnormal behavior.

I forgot to add: I have access to 2 other iPhones running iOS 10 (and with the carrier update installed) and with the same carrier as I and those iPhones have not shown this problem so far. We don't have the same apps, but the ones I use the most are in fact used also in those 2 devices.

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Answer 15

Sep 25, 2016 8:33 PM in response to rgomez

OK, thank you.

I will do that and post here the results.

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