Network Basics

From iGeek
Jump to: navigation, search

Network Basics: What is a network? A "network" is just a way to allow many devices to talk to each other.

The basics are that one device can talk to other device(s), via some shared hardware and software protocol. The protocol defines the language they speak so they can understand each other. The hardware defines the medium; whether they are talking using electricity though a wire or by using radio/light either through the air or via a light-guide (optical wire called fiber-optics).

Wired networks can be "shielded" from interference and noise easier, and so tend to allow higher speeds. But you have to physically wire facilities, which can be expensive, and then you're always tethered to the outlets and wires, which can be annoying. Plus, when wired technology changes dramatically, it may require rewiring; which is expensive. But with wired networks there is potentially more security, since in order to "break in" to your network, someone has to physically get at an access point, not just be in the proximity.

The way a network works, is that each node (device) on a network, can send and receive information. So each node is given an address; which works similar to your home address or phone number, it is just a unique identifier for that device. You obviously don't ever want two devices using the same address, because then everything gets confused over who gets what; so uniqueness of an address is important.

Addresses can be static or dynamic. Static addresses are non-changing, a network administrator manually assigns an address to each machine. Dynamic addresses can change, sometimes rarely, sometimes each time a user does something, depending on the network; but these addresses don't have to be manually assigned to each machine. Dynamic addresses are automatically figured out either by each machine (just asking all local machines what their address is and then using one that is available; AppleTalk and NetBUI do this), or more often there is just a machine, somewhere, which is the address manager. The manager gives-out a non-used address to each device that wants to use the network; so when my computer wants to use the network, it asks for (and is given) a unique address that it can use for that "session". Eventually, I turn that machine off, or enough time passes that the network takes that address back, and then that address is put back into the "available" pool. The Internet's (TCP/IP) dynamic address protocol (called DHCP) works like this.

Each device on a network is sharing the same medium (airwaves or current); so whatever a device sends, all the other devices can listen. So what the protocol does is setup rules for how they will all share that medium. Each device can only send a certain amount of information before they have to give other devices a chance to use the network as well, so there are size limits, and each chunk of information they send has to have both a target address and a return address so the network knows where the information should go, and that device knows where to return information back to. These chunks of data are called packets; and often when you send or receive a file, image, sound, etc., so it has to be broken up into many packets, and then reconstructed from parts on the other end.

Physically being on the network, and using the right protocol, lets a device (like the computer) talk to other devices on the network; but it isn't the whole story. While that gets the network working, we still have to do things like validation (account and password stuff), to know whether you have the rights to get the information you are asking for. And we not only have a device on each end, but sometimes they have many programs running, and we have to direct things to the right program; usually using a sub-address called a "port".

If you followed this somewhat dry explanation, then you have a fundamental understanding of what a network is doing, and theoretical understanding of how it is doing it.

9 items

What is a WebApp? -

What is a Web Application, and how does it vary from a traditional website? There's a joke in tech, "there is no cloud: there's just somebody else's computer": in other words, you're either using your machine, or someone else's. A traditional website is just you browsing some files (in the HTML format) on someone else's computer. And a Web Application is for things more complex than just reading files: the other computer has to be running an Application (remotely) to serve up some of the stuff you're asking for: like if you need to enter forms and have that do something, do complex lookups (searches of files), or basically do anything more complex than read/write information but interact it with in a more complex way. That's what Web Apps are for.

What is DNS? -
How the Domain Names System (DNS) works. Networks only understands addresses, and humans want a name to talk to another machine (or website) by name (like DNS is a server that translates what you type by name (iGeek), into a sort of phone number (IP address) that the network can understand. That is all.

Web Search Basics -

The basics of searching the web, or how to use Google better. Unfortunately, Web Searching is still not very good -- partly due to complexities of language, mostly due to poor implementations. But sadly, since Google and others have done a really poor job of adapting to you, you're going to have to learn how to adapt to them. Thus one of the most important things in a users "Web Experience" is learning how to search the Internet. Most users haven't spent more than 2 minutes learning how to search, and never even clicked the "advanced" search link on their favorite search engines. No wonder so many users are frustrated because they can't find anything, or find 10,000 things they don't care about.

Web Basics -

Have you ever wondered how the Web works? The majority of the Internet and computers are actually very simple to understand. The jargon and alphabet soup (acronyms) only make it sound more mysterious and complex than it really is. This article covers the basics of what happens when you go to a website.

Never trust the Internet -

Think of the internet as "the net of 1,000 lies". This is a bastion of free speech. But never forget that free does not always mean "correct"! Sometimes you get what you pay for. So trust, but verify. Heck, that's good enough advice to use it every day -- the same applies to teachers in school, and textbooks, certainly politicians, and so on. In the end, skepticism is Science and Critical thinking -- it doesn't matter what the consensus says, or any one article, it matters what you can prove to be true or false. Trust at your own peril.

Network Casting and Subnets -
What is Network casting and subnets? Networks are ways to break up information into smaller chunks (packets) and then send them over a shared line or radio frequency, to other devices, where the parts can be rebuilt into the whole again. Casting and Subnets are ways to send to many people at once, but not everyone.

EMail -
The Origins, history and evolution of eMaill, forums and live chat: basically we wanted ways to send things to others, and others wanted ways to not be interrupted and read at their convenience.

Cookies -

If you've heard Internet slang thrown around, you probably heard someone reference "cookies". What are cookies, how do they work, and what do they mean for your privacy? This article covers the basics.

Bots, Crawlers and Spiders, oh my! -

The terms bots, crawlers and spiders are likely to give arachnophobes the heebie-jeebies, but they're really just an important part of the way search engines work. The automated critters just go to the front page of a website, and look at every link in that page... then go to each of those and do the same, and so on. Once they've visited every page on a site (crawled across it), they have a pretty good idea by counting most frequent words, of what each article is about, as well as by looking at who links to that page/website, how it should rank in importance.


Written 2002.04.13