IP Addresses, Host names and DHCP Primer
What is an IP address?
Every device that is connected to the public Internet is assigned a unique number called an Internet Protocol (IP) address. IP addresses consist of four numbers separated by periods (also called a 'dotted-quad') and look something like; 127.0.0.1.
Since these numbers are normally assigned to internet service providers within region-based blocks, an IP address can be used to identify the user's general location; the region or country from which a computer is connecting to the Internet. Because the numbers are difficult to deal with, an IP address may also be assigned to a Host name, which is usually easier to remember. You can look up a hostname to find an IP addresses, and vice-versa.
What is a Hostname?
A name is a label that is used to distinguish one thing from another. A person’s name, for instance, comprises a set of alphabetic characters that allows a person to be individually addressed. Computers are also named to differentiate one machine from another and to permit activities like network communication.
Computers have always needed unique addresses to communicate with each other. With the advent of the Internet, the requirements to enable computers to communicate with each other on a network included the concept of the host-name. The hostname began as a simple string of alphanumeric characters and has evolved to its current definition, where hostname means a Fully Qualified Domain Name (FQDN) that identifies every computer hooked up to the Internet via the Domain Name Service (DNS) naming hierarchy.
The true “name” a computer needs in order to communicate on a network is a set of numbers. The original computers connected to the Internet used small integers as the host number. For TCP/IP, the main protocol used by the Internet, each computer has a network IP address that follows a specific set of rules to assure its uniqueness and validity.
At one time ISPs issued one IP address to each user, called a "static" IP addresses. Because there is a limited number of IP addresses and with increased internet usage ISPs now issue IP addresses in a dynamic fashion out of a pool of IP addresses (Using DHCP). These are referred to as dynamic IP addresses. This also limits the ability of the user to host websites, mail servers, ftp servers, etc.
DHCP
The Internet is a vast source of information that is continuously updated and accessed via computers and other devices. For a device (also referred to as a host) to connect to the Internet, it is necessary that among other configurations, it must have an Internet Protocol (IP) address. The IP address is the computer’s address on the Internet. A good comparison of an IP address would be your telephone number, which is an identifier for people to communicate with you. Configuring a computer to connect to the Internet (until the late 80s) was a manual process. The protocol Bootstrap Protocol (BOOTP) was the first Transmission Control Protocol/Internet Protocol (TCP/IP) network configuration tool used to prevent the need to manually assign IP addresses by automating the process.
While the introduction of the BOOTP network protocol was a great for network administrators who had to manage large numbers of computers on a network, it was just the first attempt. A new and improved TCP/IP network protocol soon followed. This protocol is called Dynamic Host Configuration Protocol (DHCP). DHCP wasn't designed as a replacement for BOOTP, but rather as an extension of its functionality.
How DHCP Works
As its name indicates, DHCP provides dynamic IP address assignment. This means that instead of having to rely on a specific IP address, a computer will be assigned one that is available from a subnet or “pool” assigned to the network. DHCP also extends BOOTP functionality to provide IP addresses that expire. When DHCP assigns an IP address, it actually leases the identifier to the host computer for a specific amount of time. The default lease is five days.
In basic terms, the DHCP lease process works as follows:
1. A network device attempts to connect to the Internet.
2. The network requests an IP address.
3. The DHCP server allocates (leases) the network device an IP address, which is forwarded to the network by a router.
4. DHCP updates the appropriate network servers with the IP address & other configuration information.
5. The network device accepts the IP address.
6. The IP address lease expires.
7. DHCP either reallocates the IP address or leases one that is available.
8. The network device is no longer connected to the Internet.
9. The IP address becomes an available address in the network pool of IP addresses.
To set up DHCP;
...you need a DHCP-supported client, a router and a DHCP server. The client is a computer or other device on a network that requires an IP address. The router functions as a forwarding (or routing) agent of IP address requests from the DHCP server. The DHCP server is key to the entire operation. It is responsible for allocating, leasing, reallocating, and renewing IP addresses. Windows and Linux both support DHCP software.
Every device that is connected to the public Internet is assigned a unique number called an Internet Protocol (IP) address. IP addresses consist of four numbers separated by periods (also called a 'dotted-quad') and look something like; 127.0.0.1.
Since these numbers are normally assigned to internet service providers within region-based blocks, an IP address can be used to identify the user's general location; the region or country from which a computer is connecting to the Internet. Because the numbers are difficult to deal with, an IP address may also be assigned to a Host name, which is usually easier to remember. You can look up a hostname to find an IP addresses, and vice-versa.
What is a Hostname?
A name is a label that is used to distinguish one thing from another. A person’s name, for instance, comprises a set of alphabetic characters that allows a person to be individually addressed. Computers are also named to differentiate one machine from another and to permit activities like network communication.
Computers have always needed unique addresses to communicate with each other. With the advent of the Internet, the requirements to enable computers to communicate with each other on a network included the concept of the host-name. The hostname began as a simple string of alphanumeric characters and has evolved to its current definition, where hostname means a Fully Qualified Domain Name (FQDN) that identifies every computer hooked up to the Internet via the Domain Name Service (DNS) naming hierarchy.
The true “name” a computer needs in order to communicate on a network is a set of numbers. The original computers connected to the Internet used small integers as the host number. For TCP/IP, the main protocol used by the Internet, each computer has a network IP address that follows a specific set of rules to assure its uniqueness and validity.
At one time ISPs issued one IP address to each user, called a "static" IP addresses. Because there is a limited number of IP addresses and with increased internet usage ISPs now issue IP addresses in a dynamic fashion out of a pool of IP addresses (Using DHCP). These are referred to as dynamic IP addresses. This also limits the ability of the user to host websites, mail servers, ftp servers, etc.
DHCP
The Internet is a vast source of information that is continuously updated and accessed via computers and other devices. For a device (also referred to as a host) to connect to the Internet, it is necessary that among other configurations, it must have an Internet Protocol (IP) address. The IP address is the computer’s address on the Internet. A good comparison of an IP address would be your telephone number, which is an identifier for people to communicate with you. Configuring a computer to connect to the Internet (until the late 80s) was a manual process. The protocol Bootstrap Protocol (BOOTP) was the first Transmission Control Protocol/Internet Protocol (TCP/IP) network configuration tool used to prevent the need to manually assign IP addresses by automating the process.
While the introduction of the BOOTP network protocol was a great for network administrators who had to manage large numbers of computers on a network, it was just the first attempt. A new and improved TCP/IP network protocol soon followed. This protocol is called Dynamic Host Configuration Protocol (DHCP). DHCP wasn't designed as a replacement for BOOTP, but rather as an extension of its functionality.
How DHCP Works
As its name indicates, DHCP provides dynamic IP address assignment. This means that instead of having to rely on a specific IP address, a computer will be assigned one that is available from a subnet or “pool” assigned to the network. DHCP also extends BOOTP functionality to provide IP addresses that expire. When DHCP assigns an IP address, it actually leases the identifier to the host computer for a specific amount of time. The default lease is five days.
In basic terms, the DHCP lease process works as follows:
1. A network device attempts to connect to the Internet.
2. The network requests an IP address.
3. The DHCP server allocates (leases) the network device an IP address, which is forwarded to the network by a router.
4. DHCP updates the appropriate network servers with the IP address & other configuration information.
5. The network device accepts the IP address.
6. The IP address lease expires.
7. DHCP either reallocates the IP address or leases one that is available.
8. The network device is no longer connected to the Internet.
9. The IP address becomes an available address in the network pool of IP addresses.
To set up DHCP;
...you need a DHCP-supported client, a router and a DHCP server. The client is a computer or other device on a network that requires an IP address. The router functions as a forwarding (or routing) agent of IP address requests from the DHCP server. The DHCP server is key to the entire operation. It is responsible for allocating, leasing, reallocating, and renewing IP addresses. Windows and Linux both support DHCP software.
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