Q: iOS 8.4.1 slow download

Hi how fast is your WiFi if its been over one hour stop and start again download over your WiFi .

Cheers

Brian uk

Hi. It might be true about Century Link. I have them for an ISP and my trouble was the same as yours. Something you should try, though, is going into your Settings (iOS) or Network (OS X) and change your DNS to 8.8.8.8 and 8.8.4.4. I did this on all my devices and everything works now. Just make sure to get a screenshot of your current settings before you change them.

So, for iOS: Settings / WiFi / blue info 'i' / DNS. Then tap the current set of DNS numbers and type the new numbers above. Be sure to separate the two sets with a comma as both are stored in the same text field.

For OS X: System Preferences / Network / Click the currently active network / Advanced... (button bottom right) / DNS tab at the top / click add to replace each DNS.

Make sure you press all the applicable "OK's" and "Apply's" so your new settings are locked in.

Hope it works,

Dave

BTW - this info was provided to me by an extremely efficient Apple technician in their support team. I called them after wasting much time on the phone with Century Link.

Tried the DNS 8.8.8.8, 8.8.4.4 but it didn't help.

Thank you so much! I've been trying to figure this out for hours! It was telling me I had 10 hours remaining and then it would just stop and say there was an error. I changed those settings and it downloaded within minutes! One question though. Should I change them back to the original settings once it downloads or does it matter? Thank you again! 

Yep - this worked.  Out of hours of trying to figure this out this was the answer.

Hi, auds58. I wouldn't change back to the old DNS settings.

I want to offer some comments in view of the posts above as there appears to be some misconceptions regarding what the DNS actually accomplishes. The Domain Name System (DNS) is a hierarchical naming system for computers connected to the Internet. Its main purpose is to translate domain names, which can be easily memorized by humans, to the IP addresses needed for computer services worldwide.

An common analogy is that the DNS serves as the phone book for the Internet by translating human-friendly computer hostnames into IP addresses. It has no effect whatsoever on the download speeds of large files (like system updates) once the downloading site has been located. The DNS server only has an effect while translating the hostname and it can speed this translation by a few milliseconds at best. Short of it being down, it cannot speed update downloads. Once the site has been located, the DNS process is over, you are connected to that site and are then dependent on your ISP service provider and the download site’s own servers.

The need for DNS translation is quite simple, if you were to ask the nice folks at the Apple Store what their web address is, what would you rather hear, apple.com or 17.178.96.59. How about Amazon, would you rather remember amazon.com or 176.32.98.166. If you want to test this for yourself open a Chrome or Safari page and on the search bar, type amazon.com, click enter, and as you know very well, you will see the Amazon webpage. Now open another Chrome or Safari page and do the same except this time enter 176.32.98.166. Where does it take you? To the same Amazon webpage after all. Do the same with apple.com vs 17.178.96.59 and they both will end up on the same Apple. This is true for any web page in the world.

Once the DNS server has translated the address into an IP, its job is over. Most ISPs use their own DNS server to do this translation so Century Link likely has one, AT&T who I use at home has one, etc. etc. Several of the posters above switched to Google’s own DNS servers, 8.8.8.8 and 8.8.4.4 (they have two for redundancy and are usually very reliable). However in general, slow downloads can be caused by a myriad of reasons, and only one of them would be related to the DNS, a non-responsive or overloaded server. From the anecdotal evidence provided above, it appears that Century Link had a non-responsive DNS server for the last few days and by switching DNS most of the posters above were connected to the Apple download server. Under normal circumstances, switching to a faster DNS server might improve access to high content webpages by a fraction of a second and if the site is constantly refreshing its content, a faster DNS can improve performance to some degree. This is more of an issue when surfing the web, hardly ever an issue when downloading updates unless the DNS server is down or unresponsive as I mentioned above. In that case no or very slow downloads can occur.

There is a rather easy way to test the above which I highly recommend regardless simply to verify that your ISP is providing you with the rated speeds you are paying for and secondly to test for issues like the ones above. Go to the App Store and download the OOKLA Speed Test App (free). Use the Century Link DNS and run 3 tests and average the DL speeds (make sure no one else in the household is using the Internet, only the testing device itself, best to have the others on sleep). Then switch to 8.8.8.8 and do 3 tests again. You should get about the same speeds assuming CL’s DNS server is not down (Google almost never is and they have two anyway). I just did the above and my own AT&T DNS was 1% faster than Google’s. This small amount is insignificant and irrelevant as not two tests are ever exactly the same. AT&T's load is constantly varying and their speeds fluctuate as a result.

I use Google’s DNS on all my devices simply because it is more reliable but as far as speeds is concerned, it hardly makes a difference.

Finally I wanted to answer a couple of the questions posed above.

From the OP (reigledo):

“It is taking forever for my 8.4.1 to download, read in some other forums that it's slow because of centurylink?  Is that true?”

It could have been CL or Apple. 8.4.1 was a very small upgrade (if you were going from 8.4). If the spinning wheel of death went on for an hour or more it was likely CL. Either their DNS or their Internet was down or at least very unresponsive. It would have been interesting to use another device at the same time and see how slow or fast that unit was using the OOKLA app above. I have also seen Apple’s servers slow down quite frequently. As you know they are a very large and successful entity and web traffic can be overwhelming. Imagine all those users downloading updates, restoring, etc.

From dsarmstrong:

“Just make sure to get a screenshot of your current settings before you change them.”  This is not necessary. If you decide to go back to your old settings, just do a Forget This Network and then re-join it again. After the re-join all the old settings will be back automatically from the ISP/router including CL’s own DNS numbers. The moral of this is that if you ever do a Forget for any reason or you restore your device and want Google’s DNS still, you will have to manually change it again as it will revert to the default, the ISP’s own.

From auds58:

“One question though. Should I change them back to the original settings once it downloads or does it matter?”  It does not matter, you can use whichever DNS appears to work better for you and you can use either or both of them all the time. I would leave it as-is. If you want to go back do not enter the old number manually yourself, it is too prone to errors. Just do a Forget and then join the network again. As I mentioned, I use 8.8.8.8 all the time.

I hope this helps clarify to some degree what the DNS does. Thanks to all for posting your experiences above.

elcpu

Here is an Apple article on DNS issues (for Macs but generally the same for iOS)

Non-responsive DNS server or invalid DNS configuration can cause long delay before webpages load - Apple Support