What is the difference between DHCP,Static IP,PPPOE,DDNS

[Teelak]

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Can anyone let me know what is difference between DHCP,Static IP,PPPOE,DDNS in simple words ? Which are different versions of DHCP? Is there anyone who is aware of the same and can let me know about their importance as well? A quick reply for this will be highly appreciated.

[Caelyn]

Most of the computer now a day’s uses IPv4 (Internet protocol version 4), it was created in 1981 with the capability of handling four billion IP addresses. The developer had assumed that the limit of four billion won’t run out but recently in 2011 last remaining blocks of IPv4 addresses started handing out. Anyways previously in 1980s there were few thousand of pc’s connected to Internet and as they were having four billion addresses for sharing there were no issues in handling them and each pc’s were having a static IP address. Later there was huge growth in dial-up networking because of which Customers could connect to the internet via modem. Since IP addresses were shared between isp’s only few people were able to connect once at a time. Now days there are laptops, smart-phones which connects to different networks throughout the day because of which it is not possible to assign a static ip address to them. So now using DHCP which is also known as dynamic host configuration protocol each device is assigned a different IP address as per the network to which they get connected. DHCP has a pool of IP addresses and it assigns an IP address randomly to the new users for 24 hours. The computers have to ask for a new address after 24 hours.

The benefit of having a static IP address was better than having a dynamic address. I mean one can host you’re their website, run game server, access their pc remotely across the world and so. Static IP address also provided a stable connection where as in DHCP, if DHCP lease expires in middle of a download then the process will get failed. There are a number of ISPs who offer static IP address after charging a premium amount.

[PhoebeM]

Point To Point Protocol (PPP): It is a standard protocol and is most widely used by (ISPs) for enabling dial up connections for accessing Internet. It facilitates transmission of data packets between point to point links. It has been designed to work with serial connections but it has been adopted by ISPs for providing dial up connections as well. It can be encapsulated in several data link layer protocols like Ethernet (PPPoE) and Asynchronous Transfer Mode (PPPoA). It uses Link Control Protocol (LCP) for establishing session between a pc and an ISP. LCP determines whether a link is acceptable for data transmission or not. LCP packets are exchanged between multiple network points for determining link characteristics. There are 3 types of user authentication protocols supported by PPP for providing different level of security.

• Password Authentication Protocol (PAP) - It is used for authenticating a user's password on the network access server, since the password is not encrypted in transmission, PAP is considered to be least secure.
• Challenge Handshake Authentication Protocol (CHAP) – It is a similar Protocol to PAP having unique characteristics. It sends a challenge message to the client machine which has a random value rather than requesting a password. The password is sent to access server after getting encrypted by the client machine. For authenticating user's CHAP uses shared secret model which is a secure method of authentication.
• Extensible Authentication Protocol (EAP) – It is an authentication framework and it is also used by several secure authentication protocols. It is the most common Protocol used on wireless networks for authentication.

Point To Point Protocol over Ethernet (PPPoE) : PPPoE protocol was proposed by IETF in 1999, PPPoE allows virtual point to point connection over a multipoint Ethernet network architecture, one can say that it is a protocol for expanding original capability of PPP. It is widely used to provide digital subscriber line (DSL). ADSL is most popular service of PPPoE and is a high speed Internet service, same authentication server can be used by isps for PPP as well as PPPoE sessions, PPPoE is configured as point to point connection between Ethernet ports. PPPoE session includes identification of the Media Access Control (MAC) address of the remote device which is known as PPPoE discovery.
Steps involved in PPPoE discovery as followed:

• Initiation - A PPPoE Active Discovery Initiation (PADI) packet is sent by client software to the server for initializing session.
• Offer - Server responds with a (PADO) packet (PPPoE Active Discovery Offer)
• Request - A PPPoE Active Discovery Request (PADR) packet is sent to the server by client after receiving PADO packet.
• Confirmation - A unique ID for the PPP session is generated by server and is sent as a PPPoE Active Discovery Session (PADS) confirmation packet to the client after receiving PADR packet.

In a PPPoE destination IP address is used only when session is active and the IP address is released once session gets closed.


DDNS (Dynamic DNS): It is a service for mapping Internet domain names to IP addresses. It allows users hosting a Web or FTP server for advertising a public name. It only works with static IP addresses and is for supporting dynamic IP addresses as well. It is quite good for home network where isps provide dynamic public IP addresses for various devices. A user just has to signs up with a DDNS provider after installing network software on their host to use DDNS.