What is a Dual band Router?

What is Dual Band Router?

There are four protocols and two frequencies when dealing with WiFi. What are they?

Protocols A, B G and N and Frequencies 2.4 GHz and 5 GHz.

Some routers can only emit the 2.4 GHz frequency while others can only emit the 5 GHz frequency.

The Dual Band Router can emit both frequencies

Now what does that do for you?

1.  You router is compatible with a larger range of devices (a,b,g,n)
2.  The 5 GHz is supposedly faster than the 2.4 GHz when operating at the 5 GHz frequency
3.  The 5 GHz is supposedly more stable (less interferences)

Personally I have yet to see a household networking device that uses the 5 GHz exclusively.

To go further some devices are even locked into using the 2.4 GHz band.

So to Take advantage of the 5 GHz band, your device must support it.

If you want to transfer large files wirelessly and you have the extra cash the dual band is the way to go otherwise it may not be necessary yet (at least at the time of writing).

Reference
http://www.tested.com/news/wi-fi-80211n-24-ghz-vs-5-ghz-whats-the-difference/395/
http://arstechnica.com/gadgets/guides/2011/06/ask-ars-why-do-wireless-routers-still-cost-so-much.ars

Tricks to Identify the Technologies that a Web Site is Using

I have been asked several times to identify the technologies that a particular web site is using  (from Operating System , Webserver , Javascript Framework and so on… Sometime it it very straighforward other times it is just like searching a needle in a haystack. Note that you cannot just look at the file extension to say that a website is using asp or php, you will need to dig deeper.

Here are the trick that I usually use (from the most intuitive to the least intuitive):

ONLINE TOOLS

General Info, Web server, CMS, OS…

http://builtwith.com/
http://news.netcraft.com/
http://www.quarkbase.com/
http://w3techs.com/sites

Domain Details

http://dndetails.com/
http://whois.domaintools.com/

Javascript Framework

http://nouincolor.com/wtframework/2.0/

SEO Info

http://www.alexa.com/

MANUALLY

1. If you look at the source code , if you are familiar with WordPress, Drupal and other CMS  you can easily find them by looking at the source code.
2. The CSS files can reveal a lot of information about the framework being used.

MySQL Varchar Max Length Confusion

I was always under the impression that varchar maximun length was 255.

Values in VARCHAR columns are variable-length strings. The length can be specified as a value from 0 to 255 before MySQL 5.0.3, and 0 to 65,535 in 5.0.3 and later versions. The effective maximum length of a VARCHAR in MySQL 5.0.3 and later is subject to the maximum row size (65,535 bytes, which is shared among all columns) and the character set used.

http://dev.mysql.com/doc/refman/5.0/en/char.html

Scrollbar shifts html content

As soon as your content exceeds the screen viewing area, a browser will automatically insert scrollbars to allow you to navigate up and down.
However when that happens, the content is shifted to the left, to circumvent this issue make sure that you use the css below.
(the css below will reserve a scrollbar space whether your content exceeds the viewing are or not so no more shitfing of content)

overflow-y: scroll;
overflow-x: scroll;
overflow: -moz-scrollbars-vertical;

or

body {height:101%}

Reference
http://www.brunildo.org/test/Overflowxy2.html