I want to speak about some investigations that I have made respect to some things and informatic objects we have been spoken in class. The ones which I pay more attention are:

- ROUTER

Definition:

A network device that forwards packets from one network to another. Based on internal routing tables, routers read each incoming packet and decide how to forward it. The destination address in the packets determines which interface on the router outgoing packets are directed to. In large-scale enterprise routers, the current traffic load, congestion, line costs and other factors determine which outgoing line to forward to.

At the Edge and In Between
Most routers in the world sit in homes and small offices and do nothing more than direct traffic from the network to the Internet. Sitting at the edge of the network, they may also contain a built-in firewall for security, and the firewall serves all users in the network without requiring a personal firewall in each computer.

However, in the larger company, routers are also used to separate local area networks (LANs) into subnetworks (subnets) in order to balance traffic within workgroups and to filter traffic for security purposes and policy management.

Routers in the Core
Within a large enterprise, routers serve as an internet (lower case "i") backbone that connects all internal networks, in which case they are typically connected via Ethernet. Within the global Internet (upper case "I"), routers do all the packet switching between the backbones and are typically connected via T3, ATM or SONET links.

Routable Protocols
Routers route messages transmitted only by a routable protocol such as IP "or" IPX. Multiprotocol routers support more than one; for example, IP "and" IPX. Messages in non-routable protocols, such as NetBIOS and LAT, cannot be routed, but they can be transferred from LAN to LAN via a bridge.

Because routers have to inspect the network address in the packet, they do more processing and add more overhead than a bridge or switch. Routers work at the network layer (layer 3) of the protocol, whereas bridges and switches work at the data link layer (layer 2), also known as the "MAC layer."

Specialized Machines or Regular PCs
Most routers are specialized computer-based devices optimized for communications; however, router functions can also be implemented by adding software to a server. For example, the NetWare operating system includes software to route packets from one subnetwork to another if each is connected to a separate network adapter (NIC). The major router vendors are Cisco Systems and Nortel Networks.

- COOKIES:

A small data file created by a Web server that is stored on your computer either temporarily for that session only or permanently on the hard disk (persistent cookie). Cookies provide a way for the Web site to recognize you and keep track of your preferences
Cookies Are Beneficial
Cookies are commonly used to "maintain the state" of the session as a user browses around the site. The shopping cart is an example. You can place an item in the cart, switch to another page or even another site, and when you come back, the site knows who you are, and you can continue with the order. Without cookies, the site would not be able to identify you automatically because the Internet is "stateless.
Cookies contain a range of URLs (addresses) for which they are valid. When the Web browser or other HTTP application sends a request to a Web server with those URLs again, it also sends along the related cookies. For example, if your user ID and password are stored in a cookie, it saves you from typing in the same information all over again when accessing that service the next time. By retaining user history, cookies allow the Web site to tailor the pages and create a custom experience for that individual.
Your Cookies Know You
Quite a bit of personal data may reside in the cookie files in your computer. As a result, this storehouse of private information is sometimes the object of attack