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Friday, August 5, 2011

Dynamic DNS (Domain Name System)

Every computer on the Internet require at least an IP address to be able to communicate with others. But the number of IP addresses is limited and the amount the longer wane quickly. IPv6 is designed to solve this problem but is still not commonly used. So, the ISP currently considers IP addresses as the invaluable resources and should be used with the thrifty possible. To make use of IP addresses with efficient, ISPS use dynamic IP address on the dial-up customers. That means every time a customer connect, he or she will get a different IP address. Usually this is not a problem on the activity as a client, but the entire application server may not work properly. It is similar to his situation if your phone number changes every day, your colleagues will be hard-pressed to call you.
Dynamic DNS is a method/protocol/network service that provides the capability for a networked device, such as a router or computer system using the Internet Protocol Suite, to notify a Domain Name System (DNS) name server to change, in real time, the active DNS configuration of its configured hostnames, addresses or other information.

A popular application of dynamic DNS is to provide a residential user's Internet gateway that has a variable, often changing, IP address with a well known hostname resolvable through standard DNS queries. This kind of dynamic DNS is commonly referred to as 'DynDNS', after a popular internet service of that name. It is accomplished via queries to especially formatted http/https URLs. Neither the format of these URLs nor the returned response codes is standardized. It is almost exclusively used on public networks, i.e. the internet, and does not require a user to run their own nameservers.

The standardized method of dynamically updating nameserver records is prescribed by RFC 2136, commonly known as 'Dynamic DNS Update' or 'DDNS'. Unlike the DynDNS-type updates, RFC 2136 is a protocol in its own right, with its own security mechanisms, and for use with managed nameservers. While RFC 2136 supports all DNS record types (including zone and user), it is most commonly used for dynamic hosts. In this form it is used primarily as an extension of the DHCP system, and in which the authorized DHCP servers register the clients' records with the nameservers (Windows servers are an exception: by default, Windows servers only register 'A' records and the DHCP clients are expected to register the reverse pointers). This form of support for RFC 2136 is provided by a plethora of client and server software, including those that are components of most current operating systems. Support for RFC 2136 is also an integral part of many directory services, including LDAP and Windows' Active Directory domains.


Dynamic DNS will direct a static hostname (eg: even if his IP address changes. All it takes is you have to install an email program that verify a fake POP3 email address periodically. It is necessary to inform an IP address when the DNS server dynamic service.


So, how dynamic DNS can be useful? There are many applications that can make use of static IP addresses.

The File Transfer

Transfer files over the Internet is not always a simple thing, especially if the file is very large. Smaller-sized files of 10 MB is hardly likely to be sent via email, almost the entire email server will reject an email that its size is too large. There is also no efficient way, the file will swell in size if sent via email. Upload the file to your hosting account is sometimes not possible because of limited disk space, and it also will take twice as much of the course.
With dynamic DNS you can transfer those files directly from the two dial-up account without the need for a static IP address. Call a host by using the dynamic DNS and other hosts download or upload a file is by using FTP.

The Administration Remotely :

Give the address of the dynamic DNS to your home computer and the remote administration software installing. If you leave your computer on and connected to the Internet, then you will be able to control it from your workplace, Internet cafes, or anywhere with Internet access.

Virtual Private Network (VPN)
If the Office you are still using dial-up accounts, usually it is hard to do because you don't know the VPN IP address. With dynamic DNS you and your employees can connect remotely to your office network, even if the IP address of the Internet is changing.

Audio and Visual Communication
With software such as Microsoft ® Windows ® NetMeeting ® or other software that is compatible, you can receive audio or video call. With dynamic DNS your friends will be able to call you by using an address such as

Webcam and Surveillance of the Home
With a webcam and a web server software, you can publish the pictures live to the Internet. With dynamic DNS you can easily announce the address to your colleagues. This way you can also use the webcam as your home surveillance system, so you can monitor the home, family, and others while you are in the Office.

In the initial stages of the Internet addressing of hosts on the network was achieved by static translation tables that mapped hostnames to IP addresses. The tables were maintained manually in form of the hosts file. The Domain Name System brought a method of distributing the same address information automatically online through recursive queries to remote databases configured for each network, or domain. Even this DNS facility still used static lookup tables at each participating node. IP addresses, once assigned to a particular host, rarely changed and the mechanism was initially sufficient.
However, the rapid growth of the Internet and the proliferation of personal computers in the workplace and in homes created the substantial burden for administrators of keeping track of assigned IP addresses and managing their address space. The Dynamic Host Configuration Protocol (DHCP) allowed enterprises and Internet service providers (ISPs) to assign addresses to computers automatically as they powered up. In addition, this helped conserve the address space available, since not all devices might be actively used at all times and addresses could be assigned as needed.
This feature required that DNS servers be kept current automatically as well. The first implementations of dynamic DNS fulfilled this purpose: Host computers gained the feature to notify their respective DNS server of the address they had received from a DHCP server or through self-configuration.

Some examples are complex and may require experts.

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