Page 47

DHCP (Dynamic Host Configuration Protocol)

Posted on June 24th, 2010 by Victoria Pal in Tech

DHCPDHCP stands for Dynamic Host Configuration Protocol. This protocol is used by DHCP clients to automatically obtain IP addresses. Most ISPs use it to make your life easy and be ready to browse the Internet right after you properly connect your network device.

Four steps, invisible to the user, take place before a host can obtain its IP address.


Google Showing Your Website’s Performance

Posted on June 22nd, 2010 by Victoria Pal in Tech

Google Webmaster ToolsGoogle Search Console (Webmaster Tools) is one account you can't go without on Google. It gives you so much information and enables you to tweak your sites in so many aspects that I can hardly fit all of them into a single post. Along with many of its present features - showing other sites linking to you, popular searches, sitemap submission, geographical targeting, etc., Google have recently introduced a new feature.

Site Performance is the last menu item which will appear under the "Labs" section in your Webmaster Tools account. There you can find valuable information, also available if you use a tool such as YSlow (from Yahoo) and/or Page Speed (by Google). You can learn how your pages are performing in terms of loading times. You will get a very rough comparison with the rest of the web and most valuable of all - a historical graph of your site's performance based on the loading times of each page. A graph like the one below. Under "Performance overview" you might want to see something a little bit more different to the excerpt below, but you will at least have a good start to fixing the problem.


Email Blacklists

Posted on June 17th, 2010 by Victoria Pal in Tech

email blacklistSooner or later email blacklists become the nightmare of most system administrators. Long story short - when your email provider is reported as a source of email spam, a lot of your email messages won't reach your family, friends, business partners, loyal and prospective customers alike.

Becoming part of a blacklist isn't what gets other email providers to filter you, it is the way they decide to do so. Blacklisting causes problems when the administrator decides to simply filter out all emails coming from a network device on a blacklist. Medieval doctors did a similar job when taking off an arm to save the patient from an infected finger. Clean email has no chance of reaching its intended location. Decent e-mail service providers usually filter spam, employing methods that utilize multiple filters before deciding whether an email message is spam or not.


Content Delivery Networks

Posted on June 16th, 2010 by Victoria Pal in Tech

Content Delivery Networks / CDN9Almost all of us enjoy the benefit of a Content Delivery Network, whether we realize it or not. Content Delivery Networks (CDN) also referred as Content Distribution Networks is what you call a system of network hardware containing copies of data located in various geographical locations, depending on the local demand from clients requesting the resources.

Content delivery networks are especially useful for delivering rich media content to users from different geographical locations, avoiding delay and bandwidth overload near the main server. CDNs can contain all types of data, but most often they are used to distribute data which demands high bandwidth. A few rough examples are downloadable software, media files and documentations, multimedia streams, online games as well as database queries, etc.


DDoS Attack

Posted on June 15th, 2010 by Victoria Pal in Tech

DDoS attackThe end goal of Denial-of-service attack (DoS attack) or distributed denial-of-service attack (DDoS attack) is to make a resource unavailable to its users. The attack can be carried out on different levels, depending on the target and people involved. In essence, the attack represents a highly intense attempt by one person or more to hinder web sites or specialized internet services from running properly, causing financial losses to the owner of that resource.

Depending on the motivation behind the attack, different targets might suffer from it. The attack can be implemented by a single person, carrying out a personal agenda. Such an attack is highly unlikely to cause too much trouble and will only be temporary. A much bigger problem are organized attacks performed by a group of individuals in pursuit of financial gains. Such attacks can be sustained for longer periods of time and might as well ruin companies relying on online presence. Banks, online retailers, government sites, payment gateways and even root nameservers can become easy prey for organized DDoS attacks.