DHCP Overview

In this section you will learn the DHCP router overview, dynamic host configuration protocol overview, network tutorials, troubleshooting tips, subnetting, IP addressing. DHCP or Dynamic Host Configuration Protocol is a network protocol, which is configured in such a way that is provides the IP addresses to the network computers automatically. There is no need to assign the IP address to the client computers individually. DHCP assigns the IP addresses from the given range of the numbers also called DHCP scope.

On the other end, client computers are configured in such a way that they get the IP addresses automatically from the DHCP server during the boot up process. Additionally, DNS and WINS servers can also be configured with the DHCP server.

When a computer starts up it gets the IP addresses from the DHCP server from the defined pool of addresses.

The assigning of the IP address by the DHCP server can be categorized as follows

1. A user turns on the computer with the DHCP client enabled on it.
2. The client PC sends broadcast request (known as DHCP DISCOVER) and then look for the DHCP server to answer.
3. The DHCP server receives the DISCOVER packet and based on the availability and defined settings, the server choose any available IP address and then give to the client. Then DHCP server sends back to the client with DHCP OFFER with that available address information.
4. Again client sends a request to DHCP server known as DHCP REQUEST, in which it lets the server know that it is using the address offered by the DHCP.
5. The DHCP server then again send a acknowledgement to the client known as DHCP ACK, in which it confirm the client that the specific IP address has been assigned to it for a given period of time.

This process of assigning the IP addresses by the DHCP server also known as DORA (Discover, Offer, Request, and Acknowledgement).

When a computer uses a static IP address there can be the chances of error and conflict when two computers use the same IP address. By using the DHCP server there are no chances of such kind of conflicts and errors.

Along with the IP addresses, the DHCP server also enables the client computers to extract all the settings and configurations from the DHCP server on an IP network. These settings include the Firewall, Router, DNS, NAT, WINS, Gateway and Subnet masks settings.

The overall purpose of the DHCP server is to reduce the workload and error margins, which can occur in assigning the IP addresses manually.

The IP address assigned by the DHCP server is for the limited or leased period of time and if a client needs an to extend that leased period for the IP address then client must send a extension request to the DHCP server before this period expires. If the client do not send an extension request, then this IP address becomes free on expiration and is assigned to another client. If a user wants to change the IP address given by the DHCP server then he/she do it by giving these commands on the command prompt.

“IPconfig/release then IPconfig/renew”.

This command will remove the current IP address and assign a new IP address to the client.

There can also be some reserved addresses based on the MAC address or hostname of the client. These reserved addresses are fixed addresses and can only be assigned to the fixed clients.

How to Setup a DHCP Server?

The installation of the DHCP server in the Windows 2000 or Windows 2003 is quite easy. You can install the DHCP server by using the “Manager Your Server Wizard”.

Open Manager Your Server wizard and select the DHCP server option and press next then you will be asked to enter the name and the description of the DHCP scope.

A scope is a collection of the IP addresses on subnet that use DHCP. In the next window you will be asked to define the range of the IP addresses and the appropriate subnet mask that DHCP server will distribute across the all network. Next you will see a window in which you can add anyIP address, which they don’t want to use because these are already in use for example 100.100.100.10 is an IP address of the company’s router and you don’t want that DHCP server use this address and assign to some other client.

So you can add these addresses in the exclusion field. You can define fix range of the IP addresses for exclusion. In the next step you have to assign the lease duration this means that for how long a client can use the IP address, which it got from the DHCP server. You can assign any lease duration. 10 hours, 1 week, 1 month or 1 year so on.

Next you will be asked to configure the scope of the DHCP options now or you can also configure it later.

Next the DNS and the domain name configurations and settings can be entered. The IP address of the DNS server will be assigned and distributed by the DHCP server.

Next if you have WINS requirements then you can enter the IP address of the WINS server. You can just type the server name into the box and then press resolve it will automatically resolve the name of server and find the IP address.

The next step is to activate the scope in the DHCP server because the DHCP server will not work until and unless you activate the scope. The DHCP server is now installed and you can modify the settings according the structure and the requirements of your network.

Make a plan according to the needs of your network before using the DHCP server.

Introduction to Mobile Technology and Communications

Here you will learn about mobile technologies, mobile phones, wireless communication introduction, overview to gsm, gprs, sms and mms reviews. A cellular or mobile phone is a long range portable electronic device for communication over long distance.

Current Mobile Phones can support many latest services such as SMS, GPRS, MMS, email, packet switching, WAP, Bluetooth and many more. Most of the mobile phones connect to the cellular networks and which are further connected with the PSTN (Public switching telephone network). Besides mobile communications, there is a wide range of mobile products available such mobile scanners, mobile printers and mobile labelers.

Mobile Network Technology

Mobile phones and their network vary very significantly from provider to provider and country to country. However the basic communication method of all of them is through the electromagnetic microwaves with a cell base station. The cellular companies have large antennas, which are usually mounted over towers, buildings and poles. The cell phones have low-power transceivers that transmit voice and data to the nearest sites usually within the 5 to 8 miles (8 to 13 kilometers away).

When a mobile device or phone is turned on, it registers with the mobile telephone exchange or switch. It is a unique identifier and is alerted by the mobile switch when there is an incoming phone call.

The handset listens for the strong signals from the nearest base stations. When a user moves, the mobile device handoff to various nearest sites during phone calls or while waiting between calls it reselect the nearest cell phone sites.

Cell sites have relatively less power radio transmitters. They broadcast their presence and relay communications between the mobile handsets and the switch. On the other hand, the switch connects the call to the same or another mobile network or subscriber.

The dialogue between the mobile phone handset and the cell phone site is a stream of the digital data, which includes the digitized audio. This technology depends on the same system as of mobile phone operator. Some mobile phone technologies have adopted the AMPS for the analog communication and D-AMPS, CDMA2000, EVDO, GSM, UMTS, and GPRS for the digital communication. Each mobile phone network has a unique radio frequency.

There are different mobile communication methods, such as SMS, WAP, WLAN, WIFI, GPRS, Bluetooth, Infrared, IrDA and I-Phone etc. Mobile phones are different from the cordless telephones because they only operate within the specific range. Many types of the mobile computers have been introduced including the Laptop computer, Subnotebook, Portable data terminal (PDT), Personal digital assistance (PDA), Tablet personal computer and smart phone.

Mobile phone features

Mobile phones have features beyond sending text messages and making the short or long distance voice calls, the other features including internet browsing, mp3 playback music, email, personal organizer, built in cameras, MMS, PPT, SMS, call registries, built in games, voice mails, downloading, video call, Bluetooth, infrared and they also serve as the wireless modem for a pc. In many countries of the world such as Australia, Pakistan, India, Maldives and Israel the incoming calls are free. However, in Canada, Hong Kong and the United states a person can be charged per minute for the incoming calls. Few mobile phones carriers in the United States are beginning to receive unlimited phone calls. Mobile technology has both negative and positive impact on every day’s life.

Health impact

Since the invention of the mobile phones many concerns have been raised about the potential health from the mobile phones. Study at the Danish Institute of cancer epidemiology does not show any link between cancer and mobile phone usage. This study only covers the analog phone usage till 1995. However the study by the International Agency for research on cancer shows link between cellular phone usage and tumor frequency.

Mobile dating

Mobile dating also known as cell dating and it allows users to chat, meet and possible involves in romance by SMS, chatting and the web. These services allow their subscribers to provide information about themselves in a short profile and which is stored in the cell phone sets as a dating ID. The users can search for the other IDS or call at a number given to them by the service. Users can find others with the criteria of age, location and gender. Most of these sites are free to use but the standard fees of SMS and dating service charges can apply per minute. Mobile dating websites focus attention on users that share the same social network and proximity.

Some cellular companies offer services such as homing device. This service alerts the users when someone is within the thirty feet of the user. Some cellular companies use Bluetooth technology to connect the users in the bars, clubs and social gatherings and this service is called proximity dating. These services are more popular in European countries, United States, Australia and Canada. Mobile dating websites are gaining popularity.

Mobile Learning

M-learning’ is the follow up of E-learning and which originates from D-learning (distance learning). M-learning is the delivery of education to the students who are not having fixed location or who prefer to use mobile phone technology for learning. The rapid growth in the mobile and communication sector make it possible to develop new forms of education. M-learning means delivery of education by means of the mobile phone devices, PDAs and audio players. M-learners seek the lessons in the small format.

Mobile software

Windows mobile, Palm OS and Symbian OS supports typical application binaries as found on the personal computers. Windows mobile also supports portable executable format which is associated with the .NET Framework. Both Windows Mobile and Palm OS provide free SDK and integrated development environment for the developers. BREW is another format which gives complete control of the handset and access to all its functions. Java (J2ME, Java ME) runs atop a virtual machine, which allows reasonable functionalities. Because of the extra security and compatibility, it is quite simple to write, distribute and execute the mobile Java applications.

Mobile Internet

According to the many sources, one of the major factors of the usage of mobile internet is its speed. Mobile internet has faster connection. Due to this fact, many users tend to use mobile internet. The introduction of the 3G cards has a competitive high speed. All the current service providers and trying to increase their bandwidth to get more customers. The numbers of mobile phones that are cable of surfing the net have been increasing rapidly. One of the greatest problems when browsing the net on the cell phones is the small size of the screen. Because of this many developers are developing the websites that can easily be seen on the cell phones as well.

Mobile society.

Ongoing debates about the cyberspace, e-computing and E-commerce have suggested that the online world somehow will be dramatically different from the life in the analog world. It is true that E-commerce continues to grow and the specific locations of the persons and businesses do not matter that much anyone. This is also true that now we are seeing forums, blogs, discussion groups and social network to re-socialize and form new tribes on the internet. It seems that everyday we are increasingly connected via technologies such as email, cellular phones, instant messaging and all of these technologies are increasingly interconnected with each other. When we communicate on our cell phones, we are also mobile in the sense that we can move freely while in the constant communication.

Here Mobile Phones you will learn about the mobile technologies, cellular phones, wireless communication introduction, overview to gsm, gprs, sms and mms reviews.