China with its largest population of web users in the world, has one of the most restricted internets, making sure that netizens cannot post nor read about information the government deems threatening.

The robots.txt file simply contains instructions for search engine robots on what to do with a particular website. While the search engine robots follow the instructions from that file, spam bots simply ignore it in most cases.

A web robot is a program that checks the content of a web page. If a robot is about to crawl a website, it will first check the robots.txt file for instructions. A command “Disallow”, for example, tells the robot not to visit a given set of pages on this site. Web administrators use this file to restrict the bots to index the content of a particular website for different reasons - they do not want the content to be accessible by other users; the website is under construction, or a certain part of the content must be hidden from the public.

The importance of “expires header” is growing along with the web page designs which are becoming richer in scripts, images, Flash, etc.

As a result of the growing complexity of web designs, a web page takes longer to load, which is why the site needs an expires header. It simply makes all components such as stylesheets, images and others cacheable or, in other words, prevents unnecessary HTTP requests after the first page view and hence load time is reduced.

Many people who run a business website overlook the importance of the domain name and its expiration date, and they only hear about it when the website is already down. Well, it is crucial to avoid domain name expiration because it could harm both your business and reputation significantly.

If you forget to renew your domain, you will stop receiving e-mails through your website; the website will simply be not there and replaced with ads. The best case scenario is to lose the site, but still be able to register it.

The service code 503 simply implies that the server is unable to handle a request due to overloading or maintenance of the server. It is important to note that although this condition is temporary and simply causes some delay, some servers may refuse the socket connection, which will result in a different 5xx error code.

Here’s what happens when the browser tries to communicate with the web server: