TechnoBlabber

Cogitative blurbs on all things mobile

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The GPRS tweak that doesn’t work

December 10th, 2006 by abhishta

Lots of blogs and forums are talking about a tweak which supposedly increases your GPRS browsing speeds. The tweak involves changing your DNS server address. Now, let me make this clear,

DNS servers have nothing to do with transfer rates.

A DNS server is basically used to convert a hostname/url like “www.abhishta.net” to a corresponding I.P. address like “192.168.1.1”. It will not improve loading times, download rates in any way.

But some users reported an increase in their browsing speeds. How did this happen? Let me explain it to you in brief:

A GSM system uses TDM or Time division Multiplexing, wherein each user transmits in predefined time slots. Since GPRS/EDGE is an overlay over GSM, it works in the same way. Initially, the network starts your connection by assigning you a single slot with the most conservative data rate. As it sees that your bandwidth requirement increases, it will try to increase your data rate by decreasing the coding rate (you still transmit in a single slot) if the channel conditions permit. However, if that is not enough, it will then try and assign you extra time slots to transmit, provided the network is not busy. Thus, your data rate increases gradually as you start your packet data session. So if you started your speed test with the network default settings and found your data rate to be say, 50kbps and then if you changed your DNS settings and re-ran the test, the network knowing that you have an active data connection, will allocate additional resources to you. That’s why you see an immediate increase in your speeds.

I would STRONGLY recommend people to keep the DNS server to the network default as a bad DNS server could lead to DNS spoofing.

Let us take the example of a bank, say for example, Bank of America. Its url is “www.bankofamerica.com” and its actual IP address might be 129.2.24.23 (hypothetical IP address). And this is available in your DNS server. Now, someone comes along and says, change your DNS server to blah blah and you will get better speeds. Trusting him, you do it. In the new DNS server, www.bankofamerica.com is now mapped to IP address 129.24.56.20 which belongs to a hacker. The hacker runs a web server from that IP address and hosts a spoofed version of the bank of america website. And on that duplicate website, the moment you enter your username and password, it gets stored into the hacker’s database and your identity is compromised.

That’s why I will always recommend never to change settings that you don’t know about.

Tags:   · 2 Comments

  • http://s60.blogg.se Henrik

    I suppose your writing about the thing I wrote on my blog. First of all I just want to say that my idea with this wasnt to increase the bandwith somehow, but just improve the time in the connection phase, when connecting to the operator.

    I have done a lot of tests, and based on those facts I wrote the guide.

    How people use it, for what pages they are going to I have no control over…I do however agree with you that it might be risky depending on what kind of services you use from your phone…but thats apply also to a PC user. Maybe my blog isnt aimed for N00bs 😉

    Cheers,

    Henrik

  • http://www.aparanjpe.com abhishta

    People started spreading this tweak as a means to “speed up your gprs connection” and to get more transfer rates. I’m sure you had the right intentions when u posted this tweak. My post was only to warn people about the hazards of blindly changing settings on their cellphones. 😉
    But it was an interesting social experiment of sorts.