There is little that is more frustrating than a webpage that takes a long time to load, or never loads at all.
It’s even more frustrating when you’ve got one of the latest, fast
Macs that is connected to a superfast broadband (or normal broadband,
for that matter) connection. You can be close to tearing your hair out
wondering why webpages are slow to load. If this is your experience then
this tutorial may have the answer.
Please Explain More
Safari, from version 5.0.1 onwards, employs a technique known as DNS
prefetching. This is designed to ensure that webpages load faster. On
occasion it can, unfortunately, have the opposite effect meaning that
webpages can take a long time to load. Or simply not load at all.
The DNS Prefetching Problem
The problem of slow, or non-loading, webpages is often caused by DNS
prefetching. First, let’s examine the DNS bit and then the prefetching
aspect.
DNS Explained
DNS is the Domain Name Server (or system) that associates IP (Internet Protocol) addresses with domain names.
IP addresses are strings of numbers such as 212.58.244.69. Entering that number into a web browser will take you to the BBC website, as would entering bbc.co.uk. Being human, we find the latter easier to remember.
The analogy that is often used is that DNS works like a telephone
directory for the internet in that it translates names (domain names)
into numbers (IP addresses).
Prefetching Explained
Prefetching, in the context of DNS, is an attempt to resolve domain names before the web browser user attempts to follow a link.
The reason that this is done is that DNS resolution time – the time
taken to look up and translate a domain name to an IP address (remember
the phone directory analogy and how long it might take you to look up
someone’s number) – can lead to a variable delays that contribute to
user-percieved latency. That’s to say, how long you think the delay is
in the webpage, from a new website, downloading.
The Solutions
There are two main solutions to the DNS prefetching problem. They are
to first try an alternate DNS service. Using our telephone directory
analogy, once more, it’s akin to using a Thomson Local, rather than
Yellow Pages, to look up the required information.
The second is to disable DNS prefetching altogether.
Try a Different DNS Service
The purpose of trying a different DNS service is to rule out any
issues with the DNS service used by your ISP (Internet Service
Provider).
Two of the main DNS service providers are OpenDNS and Google DNS.
Alternatively, you can search the internet for third party DNS services
for more options.
You can change your DNS service settings either on each Mac that you
own or, if you use all your Macs in one place such as a home or office
network, you can update the DNS service settings on your router or Apple
Time Capsule. OpenDNS may prove more reliable than your ISP's DNS
Disable DNS Prefetching
If the issue of slow, or non-loading, webpages persists, the next
step is to disable DNS prefetching using a command in terminal.
Tip: Terminal is not for those who do not understand
what they are doing. It is possible to compromise the smooth operation
of OS X if you enter the wrong command. That said, you can copy the
command from this article and paste it into terminal to ensure that it
is entered correctly.
First, ensure that you have quit the Safari app. Then open up the Terminal app which is located in /Applications/Utilities.
When you see the command prompt, enter the following command. The command that you are entering will disable DNS prefetching.
Now relaunch Safari and test for the slow, or non-loading, webpage issue on any websites where you were having the problem.
Check Your Router
If disabling DNS Prefetching, with the terminal command, has solved
your issue, then the root cause of the problem may lie with your router. Check your router, AirPort Extreme or TimeCapsule
In order to determine if this is the case, check to see if your
router’s manufacturer has issued a firmware upgrade in the time since
you acquired your router. It may be that they have issued an upgrade
that is intended to fix a number of issues and/or introduce new
functionality to the device.
Visit the website for the manufacturer of your router to determine if
firmware updates are available and, if they are, be sure to follow the
installation instructions very carefully so as not to compromise the
functionality of the router itself.
If your router is particularly old, it may be wise to upgrade to a more modern and robust device.
Having checked for the latest firmware on your existing router, or
having replaced an old router with a new one, the next step would be to
re-enable DNS prefetching.
How to Re-enable DNS Prefetching
Quit Safari and open the Terminal app, located in /Applications/Utilities.
When you see the command prompt, enter the following command. The command that you are entering will re-enable DNS prefetching.
Relaunch Safari and test by visiting any website with which you were
previously experiencing problems with slow, or non-loading, webpages.
Advertisement
The Final Solution
After having upgraded your existing router’s firmware, or upgraded to
a modern router, and re-enabling DNS prefetching you are still
experiencing slow, or non-loading, webpages then the final solution
would be to disable DNS prefetching once more.
Simply follow the earlier instruction for the Terminal command to disable DNS prefetching in Safari and leave it at that.
Conclusion
Having followed the instructions in this tutorial, you should now be
viewing previously problematic websites without any slow, or
non-loading, webpages.
If the solution for your was to disable DNS prefetching then your
browser will not be looking up links to other websites before you click
through to them. On occasion, and depending upon the DNS system, it may
take a little while for the domain name to resolve to an IP address
before the website loads in the browser.
Normally speaking, you will not notice any delay in domain name
resolution except for in exceptional circumstances. Either way, the
webpage performance should now have improved on the sites with which you
were previously experiencing problems.
A
regular contributor to Mac, iPad and iPhone AppStorm sites, Johnny has
been online since 1995 aiming to use the internet for the creation and
sharing of knowledge for the greater good. Via setting up forums and
e-commerce businesses, Johnny is an accidental podcaster and Editor of
Mac Computer Skills at hub.tutsplus.com
Lorem ipsum dolor sit amet, consectetur adipisicing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation.
Medical Disclaimer
The information on this site is not intended or implied to be a substitute for professional medical advice, diagnosis or treatment. All content, including text, graphics, images and information, contained on or available through this web site is for general information purposes only. Krobknea makes no representation and assumes no responsibility for the accuracy of information contained on or available through this web site, and such information is subject to change without notice. You are encouraged to confirm any information obtained from or through this web site with other sources, and review all information regarding any medical condition or treatment with your physician. NEVER DISREGARD PROFESSIONAL MEDICAL ADVICE OR DELAY SEEKING MEDICAL TREATMENT BECAUSE OF SOMETHING YOU HAVE READ ON OR ACCESSED THROUGH THIS WEB SITE.
