Pengertian Dan Fungsi Server

Server adalah sebuah sistem komputer yang menyediakan jenis layanan tertentu dalam sebuah jaringan komputer server didukung dengan prosessor yang bersifat scalable dan Ram yang besar. Ianya juga dilengkapi dengan sistem operasi khusus yang disebut sebagai sistem operasi jaringan.
Umumnya, dalam sistem operasi server terdapat berbagai macam layanan yang menggunakan arkitektur client/server.  Contoh dari layanan ini adalah Dynamic Host Control Protocol (DHCP), Mail Server, server Pth, Server Ptb, DNS server dan lain-lain.


Fungsi Server :
Dilihat dari fungsinya, server terbahagi dari beberapa macam jenis, seperti :

• Server Aplikasi
• Server Data
• Server Proksi

Server Aplikasi Adalah Server yang di gunakan untuk menyimpan berbagai macam bentuk aplikasi yang dapat diakses oleh client.

Server Data digunakan untuk menyimpan data baik yang digunakan klien secara langsung maupun data yang diperoleh dari server aplikasi.

Server proksi berfungsi untuk mengatur lalu lintas di jaringan melalui pengaturan proksi.


Kredit: http://e-komputer.blogspot.my

TCP/IP and Subnet Mask

Tutorial by Eli

Voice Over Internet Protocol (VOIP)

Alternatively referred to as IP telephone or Internet phone,  VoIP is short for Voice over Internet Protocol and is an Internet protocol that enables users to make calls over the Internet. 

VOIP, a category of hardware and software that enables people to use the Internet as the transmission medium for telephone calls by sending voice data in packets using IP rather than by traditional circuit transmissions..." (quoted from Webopedia Computer Dictionary).

To make a call a telephone is connected to a network cable, versus a standard phone line or a call is made over a computer. This enables long distant phone calls to be cheaper, although sometimes at a lower audio quality. The first experiment VoIP call was made in 1973 even though the first software known as "Vocaltec" that enabled end users to make calls did not appear until 1995.

Today, VoIP and Internet phones are becoming commonplace. Many cable TV providers offer bundles that include VoIP, allowing customers to take advantage of the Internet phone technology. Businesses have begun to embracing the change and utilize VoIP as well, nearly eliminating the need for telephone lines in the work place. While telephone lines are not completely gone, technology is moving things in that direction and it may not be long before the Internet phone, and the cell phone are the remaining two primary methods for voice communication.

Examples of VoIP include: Skype, Teamspeak, and Ventrilo.

Uses

VOIP has become a growing method of communication in the modern world, especially in sales-oriented jobs. It has been integrated mostly for business purposes to replace conventional phone calls. The methods of use can be classified into three major categories:

• To interconnect VOIP phones within a single building using the building's Local Area Network (LAN)
• To interconnect VOIP phones between multiple locations of the same organization using a backbone network
• To interconnect VOIP phones to regular telephones in different organizations or for sales purposes

Benefits

Toll-Free Calls

The main purpose of VOIP is to provide a method of cheap yet extensive communication. Regular telephone calls can become costly if used too frequently, yet with VOIP one only needs to pay for a good internet connection and subscription to a VOIP service. With these two facilities handy, VOIP becomes a capability to make limitless phone calls through the internet. Although the person at the other end may be using a regular phone, the VOIP user either uses a computer or VOIP phone to communicate.

The major advantage of VOIP is that it allows the user to make as many phone calls as they like for a fixed price instead of being charged by the minute. This makes a huge cutback on costs for jobs such as telephone marketing that require making many phone calls for hours every day.
VOIP can become low-cost or toll-free for people who are using only the internet to communicate. If both or all users are using the internet to communicate, VOIP becomes a way of talking or conferencing without having to pay any additional fee apart from the regular fee for internet.

Reduced Wiring Costs

Using VOIP can also minimize building wiring costs in new or renovated buildings due to reduced wire infrastructure. Instead of using many cable systems such as data networking, telephone connections, and cable distribution, VOIP makes it possible to rely on less cabling costs in terms of maintenance as well as initial installment.

Easy Relocation

Anyone who has relocated their job or home knows how difficult it is to switch local phone numbers, not only for them but even more so for others who want to call them. Cell phones have largely helped to solve this problem, but cell phones are one of the costliest methods of common communication. VOIP provides a cheaper solution, since internet is a universal medium. A VOIP instrument can be relocated without central administrative support. With the internet being a global medium, VOIP allows users to communicate from anywhere in the world at one of the lowest costs possible.

Roaming Facility

To use your regular local phone you have to access it from your regular phone line. It would not be possible for you to make a phone call using your local phone line if you are somewhere else using someone else's phone. Here is another problem that VOIP helps us overcome. With VOIP, you can use someone else's phone to use your VOIP connection. Some VOIP systems allow people to walk up to a telephone instrument in any office and dial a couple of numbers on the keypad ("log in"). That telephone then temporarily assumes the configuration of the telephone line in your home office. By assuming your telephone number, your list of speed dial numbers, and your intercom settings, it becomes a temporary substitute for your VOIP phone in your office!

Dynamic IP vs Static IP

Static IP addressing is for one customer on one IP address and Dynamic IP addressing assigns a different IP address each time the ISP customer logs on to their computer, but this is dependent upon the Internet Service Provider (ISP) because some ISP's only change the IP address as they deem it necessary.

If you have Dynamic IP Addressing through your Website Host it means that you are sharing an IP Address with several other customers.
If you are a beginner on the internet, an avid internet user, are entertaining the thought of starting your own website business, are a gamer, use VOIP or VPN there are several things you should know about IP Addressing.

Static IP Addressing

If you feel the need to always know what your IP address is then you need a Static IP address, because it is constant. Static IP addresses are more reliable for Voice over Internet Protocol (VOIP), more reliable to host a gaming website or to play X-Box, Play Station, use Virtual Private Network for secure access to files from your company network computer, etc. 

Static IP addresses are also great if you use your computer as a server, as it should give your file server faster file uploads and downloads. Another plus with Static IP's, when hosting a website you are not sharing your IP with another company who sends out a lot of E-mail SPAM and not only has their website been shut down but in turn gets your IP address blacklisted.

In contrast a static IP address can become a security risk, because the address is always the same. Static IP's are easier to track for data mining companies. Static IP addressing is less cost effective than Dynamic IP Addressing.

Dynamic IP Addressing

The biggest advantages of Dynamic IP Addressing are less security risk as the computer is assigned a new IP address each time the customer logs on, they are cost effective and there is automatic network configuration (the less human intervention with network configuration the better). Dynamic addressing is usually used by ISP's so that one IP address can be assigned to several users, however some ISP's use Sticky Dynamic IP Addressing and do not change the IP address very often. Dynamic IP Addressing can be used by families with several computers or by a small business owner who has a home office. The software that comes with a router allows for Dynamic Host Configuration Protocol (DHCP) setup and assigns each computer attached to the router an IP address automatically.

In contrast, Dynamic IP addressing should not be used for VOIP, VPN, playing online games or game hosting because Dynamic IP addressing is less reliable then Static IP addressing and could cause the service to disconnect while you are on a VOIP, VPN or gaming.

Source: http://whatismyipaddress.com

PoE Injector And PoE Splitter

PoE Injector
Reduce costs by using existing Cat5 cable to provide both power and data.

Power over Ethernet Injector allows you to connect your IEEE 802.3af-compliant products to a non-PoE LAN switch port. The injector can be used to connect a wireless access point, IP phone, network camera or any IEEE 802.3af powered device (PD) to a switch.

Reduce Wiring Costs
No need to run AC power lines for your wireless access point, network camera or IP phone. Simply connect the PoE Injector to the LAN switch port, and use the existing Cat5 cabling to deliver DC power as well as transfer data.

PoE Splitter
Deliver Power over Ethernet to remote devices.

PoE Splitter allows you to deliver both data and electrical power to non-PoE Ethernet-enabled products using the Cat5 Ethernet cable. Using the PoE Splitter, you can take advantage of Power over Ethernet and place Ethernet-enabled products, such as Network Cameras and Wireless Access Points*, where power outlets are not readily available.

Simplify Installation for an Ethernet-based Device
Having to manage only an Ethernet cable simplifies the physical installation of the device. Without having to worry about the availability of a power source, you can mount Ethernet-enabled products on a ceiling or outdoors, up to 100m (328 feet)** from a power source. The PoE Splitter is simple to install and requires no tools or software.

802.3af Compliant Power over Ethernet
The PoE Splitter can be used to complement any PoE injector unit or midspan switch to provide small to medium-sized businesses a complete end-to-end PoE solution. This unit supports 802.3af, ensuring compatibility with other 802.3af PoE-compliant injector units or midspan switches.

Understanding The Basics Of Cloud Computing

Cloud Computing

Although no longer quite the buzzword that it was back in 2011, it’s clear that the cloud is here to stay, even though some still find cloud storage hard to trust. As demand grows for faster, higher-resolution videos and games – especially on smaller and smaller devices – our dependence on cloud storage and cloud computing will only increase. But what does “the cloud” actually mean to you? It can be unnerving to rely on cloud technology without fully understanding how it works, so read on for a more substantial grasp of what’s happening.

Meaning of the cloud

The first thing to understand is that “the cloud” is simply a metaphor for various data networks, generally located somewhere far away and accessed via the internet. Despite what the name suggests, it has nothing to do with the stratosphere – and no, stormy weather can’t interfere with cloud computing, at least not unless there’s a major power outage.

As a metaphor, “the cloud” simply denotes vast, distant clusters that we may not be able to interact with physically, yet which still affect us. In cloud computing, the clusters of servers, fiber-optic cables, and software engineers may be far away, but we can still interact with them by sending information back and forth. Another good analogy is the way households pull electricity from the electricity grid. Without ever visiting a power plant or connecting a power line themselves, families are able to benefit from a massive, shared network that provides them with a much-needed service.

Types of cloud computing services

If this definition of the cloud sounds huge and all-encompassing, that’s because it is. There are a wide variety of possible cloud computing services. The three types most likely to be useful to consumers and businesses are Infrastructure as a Service, Platform as a Service, and Software as a Service.

1. Infrastructure as a Service (IaaS)
This is the foundation, or “base layer,” of cloud computing, and includes physical infrastructure such as servers, storage disks, and facilities. Organizations benefit from pay-as-you-go, on-demand storage and web hosting, which can be easily scaled bigger or smaller as need fluctuates.

2. Platform as a Service (PaaS)
This “middle layer” of cloud computing provides the operating system from which applications run. Here, the service operator provides a programming language and web server, which allows application developers to create and run their software solutions.

3. Software as a Service (SaaS)
Finally, at the “top layer,” we find software applications specifically developed for the internet. Here, consumers generally pay a monthly or yearly fee in order to use a certain software in the cloud (as opposed to traditional software, which requires a single, up-front cost for perpetual use). Because pricing is pay-per-user, organizations can quickly add or remove users without having to accordingly scale their associated platform and infrastructure. This on-demand approach allows for rapid, efficient adjustments in staffing. Examples include Salesforce, Google Apps (Gmail, Google Calendar, Google Docs), and Microsoft OneDrive and Microsoft Office 365.

Types of cloud storage services

Of course, for the average computer user, some of the most important SaaS offerings are cloud storage services. These allow file hosting, file sharing, and remote data backup. Basically, after signing up for a cloud storage service, you get a certain amount of free storage space (usually 2–5 GB) for hosting whatever data you would like, along with the option to pay for an upgrade to access more storage space. Just like with other SaaS software, you can increase or decrease your use of the service very quickly, without having to interact with any of the related computing infrastructure.

What Is An IP Address?

No doubt you've heard the term "IP address." Unless you're a techie, though, you may not have more than a shadowy notion of what an IP address actually is or how it works. Let's explore the concept.

An IP address is a fascinating product of modern computer technology designed to allow one computer (or other digital device) to communicate with another via the Internet. IP addresses allow the location of literally billions of digital devices that are connected to the Internet to be pinpointed and differentiated from other devices. In the same sense that someone needs your mailing address to send you a letter, a remote computer needs your IP address to communicate with your computer.

"IP" stands for Internet Protocol, so an IP address is an Internet Protocol address. What does that mean? An Internet Protocol is a set of rules that govern Internet activity and facilitate completion of a variety of actions on the World Wide Web. Therefore an Internet Protocol address is part of the systematically laid out interconnected grid that governs online communication by identifying both initiating devices and various Internet destinations, thereby making two-way communication possible.

An IP address consists of four numbers, each of which contains one to three digits, with a single dot (.) separating each number or set of digits. Each of the four numbers can range from 0 to 255. Here's an example of what an IP address might look like: 78.125.0.209. This innocuous-looking group of four numbers is the key that empowers you and me to send and retrieve data over our Internet connections, ensuring that our messages, as well as our requests for data and the data we've requested, will reach their correct Internet destinations. Without this numeric protocol, sending and receiving data over the World Wide Web would be impossible.

IP addresses can be either static or dynamic. Static IP addresses never change. They serve as a permanent Internet address and provide a simple and reliable way for remote computers to contact you. Static IP addresses reveal such information as the continent, country, region, and city in which a computer is located; the ISP (Internet Service Provider) that services that particular computer; and such technical information as the precise latitude and longitude of the country, as well as the locale, of the computer. Many websites provide IP address look-up services to their visitors, free of charge. If you're curious about your own IP address, you can locate these websites by performing a Google search.

Dynamic IP addresses are temporary and are assigned each time a computer accesses the Internet. They are, in effect, borrowed from a pool of IP addresses that are shared among various computers. Since a limited number of static IP addresses are available, many ISPs reserve a portion of their assigned addresses for sharing among their subscribers in this way. This lowers costs and allows them to service far more subscribers than they otherwise could.

Static IP addresses are generally preferable for such uses as VOIP (Voice over Internet Protocol), online gaming, or any other purpose where users need to make it easy for other computers to locate and connect to them. Easy access can also be facilitated when using a dynamic IP address through the use of a dynamic DNS service, which enables other computers to find you even though you may be using a temporary, one-time IP address. This often entails an extra charge, however, so check with your ISP.

Static IP addresses are considered somewhat less secure than dynamic IP addresses, since they are easier to track for data mining purposes. However, following safe Internet practices can help mitigate this potential problem and keep your computer secure no matter what type of IP address you use.

IP Address: What Is DHCP?

As long as you're learning about your IP address, you should learn a little about something called DHCP—which stands for Dynamic Host Configuration Protocol. Why bother? Because it has a direct impact on millions of IP addresses, most likely including yours.

DHCP is at the heart of assigning you (and everyone) their IP address. The key word in DHCP is protocol—the guiding rules and process for Internet connections for everyone, everywhere. DHCP is consistent, accurate and works the same for every computer. Remember that without an IP address, you would not be able to receive the information you requested. As you've learned (by reading IP: 101), your IP address tells the Internet to send the information that you requested (Web page, email, data, etc.) right to the computer that requested it.

Those incredible protocols

There are more than one billion computers in the world, and each individual computer needs its own IP address whenever it's online. The TCP/IP protocols (our computers' built-in, internal networking software) include a DHCP protocol. It automatically assigns and keeps tabs of IP addresses and any "subnetworks" that require them. Nearly all IP addresses are dynamic, as opposed to "static" IP addresses that never change.

DHCP is a part of the "application layer," which is just one of the several TCP/IP protocols. All of the processing and figuring out of what to send to whom happens virtually instantly.

Clients and servers

The networking world classifies computers into two distinctive categories: 1) individual computers, called "hosts," and 2) computers that help process and send data (called "servers"). A DHCP server is one computer on the network that has a number of IP address at its disposal to assign to the computers/hosts on that network. If you use a cable company for Internet access, making them your Internet Service Provider, they likely are your DHCP server.

Permission slips

Think of getting an IP address as similar to obtaining a special permission slip from the DHCP server to use the Internet. In this scenario, you are the DHCP client—whenever you want to go on the Internet, your computer automatically requests an IP address from the network's DHCP server. If there's one available, the DHCP server sends a response containing an IP address to your computer.

How DHCP works

The key word in DHCP is "dynamic." Because instead of having just one fixed and specific IP address, most computers will be assigned one that is available from a subnet or "pool" that is assigned to the network. The Internet isn't one big computer in one big location. It's an interconnected network of networks, all created to make one-on-one connections between any two clients that want to exchange information.

One of the features of DHCP is that it provides IP addresses that "expire." When DHCP assigns an IP address, it actually leases that connection identifier to the user's computer for a specific amount of time. The default lease is five days.
Here is how the DHCP process works when you go online:

1. Your go on your computer to connect to the Internet.
2. The network requests an IP address (this is actually referred to as a DHCP discover message).
3. On behalf of your computer's request, the DHCP server allocates (leases) to your computer an IP address. This is referred to as the DHCP offer message.
4. Your computer (remember—you're the DHCP client) takes the first IP address offer that comes along. It then responds with a DHCP request message that verifies the IP address that's been offered and accepted.
5. DHCP then updates the appropriate network servers with the IP address and other configuration information for your computer.
6. Your computer (or whatever network device you're using) accepts the IP address for the lease term.

Typically, a DHCP server renews your lease automatically, without you (or even a network administrator) having to do anything. However, if that IP address's lease expires, you'll be assigned a new IP address using the same DHCP protocols.

Here's the best part: You wouldn't even be aware of it, unless you happened to check your IP address. Your Internet usage would continue as before. DHCP takes place rather instantly, and entirely behind the scenes. We, as everyday, ordinary computer users, never have to think twice about it. We just get to enjoy this amazing and instantaneous technology that brings the Internet to our fingertips when we open our browsers. I guess you could say DHCP stands for "darn handy computer process"...or something like that.

What You Should Know About IP Address?

We figured that many of ICT students don't know a lot about IP topics—and why would you? For the most part, only IT (information technology) and computer-network types have the need to think about such things.

Still, sometimes the terminology and jargon used (and rarely explained) prevents us from understanding come cool computer stuff. And although most of us don't really care (or need) to learn more, others like being enlightened, instead of being left in the dark.
So, here is a brief list of facts regarding the abbreviation "IP."

1. IP ("eye-pea") is actually part of a longer abbreviation — TCP/IP. That stands for Transmission Control Protocol/Internet Protocol. (We'll call it IP for short.)
2. IP stands for 'Internet Protocol.' A protocol is a guideline that must be followed in a set, specific way.
3. IP is actually networking software. It comes with your computer and it makes make it possible for you to interact with the Internet.
4. IP is the language of the Internet (so to speak): All IP networking software is identical throughout the world; that's why a computer in China can communicate with a computer in Canada.
5. IP is universal. No matter what kind of computer or networking hardware you're using, the IP processes work the same.
6. IP is versatile. Any computer, laptop or desktop, or printer on a network has IP software (and therefore an IP address).
7. The TCP/IP Protocols are actually a set (or stack) of protocols that work in sequence. Think of the set as a team of robot—soldiers who receive, handle and disburse data.
8. The Internet Protocol is at the heart of the network connectivity. It is also where IP address activity gets processed.
9. Any device on a network has and needs an IP Address. That address is a set of numbers and dots. Want to see yours right now? Click here.
10. Computers identify websites by their IP addresses. Fortunately for you, they typically go by their names, like  www.yahoo.com

Introducing WANs

Tutorial by Anthony Sequeira

Introduction to DHCP

Tutorial by Eli

Network Cabling

Tutorial by Eli