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Ddns- How it Works? Own Mail Server? Own Www Server? it is Possible Even in your Home

What is DDNS?

If we wish to run a server for website hosting or accessing CCTV cameras, available from any Internet location - and we don't have a static IP address but a dynamic one supplied by DHCP server (e.g. ADSL service) - we have to use DDNS (Dynamic Domain Name System). DDNS server provides a database containing relations between domain names and numeric addresses, which may be updated on request, by the domain owner. Thanks to this feature, the server is available in the domain name regardless its current IP address. We have to remember that when DHCP server changes the IP, it takes some time to detect this change by the client software or router. Then, after the notification has been sent to DDNS server, it takes another minute or so to send this piece of data to DNS server to update the database. As a result, our server will be periodically unavailable up to several minutes - every time the IP address has been changed. To use the service one has register at a DDNS server, e.g.:


It is also needed to have a router capable of sending current IP address to the DDNS server. From the TP-Link offer there may be used access points with integrated routers and ADSL modems, like TP-Link TD-W8910G and TD-W8920G, or routers with ADSL modems - TP-Link TD-8840 or TD-8841.

DNS (Domain Name System)

is a service translating an IP address from numeric to domain name. It means that there is no need to memorize addresses in numeric form such as 62.121.128.13 - you can always use adequate name, for example www.dipol.com.pl. DNS server will translate the numeric address into domain name on request. After the computer which made the request receives the numeric address, it can establish connection with the appropriate computer.

Such communication is possible if the server has a static IP, at which it is always available. A single record in DNS server database establishes relation between the addresses 62.121.128.13 and www.dipol.com.pl. This relation is always valid and invariable, so the client can communicate with the server either through domain name (using DNS translation) or directly via numeric address (bypassing DNS server).

What is a DDNS?

If we wish to run a server for website hosting or accessing CCTV camera, available from any Internet location and we don't have a static IP address but a dynamic one supplied by DHCP server (Neostrada - ADSL service in Poland is a good example of such an option), we have to use DDNS (Dynamic Domain Name System) service.

How does DDNS work?

Neostrada clients do not have a static IP - it is changed periodically. As we have shown above, in this situation it is impossible to run a server, because the current IP address of the server would have been unknown. DNS server, which translates domain name into numeric form, points at one specific IP. Once the IP number changes, the DNS data ceases to be valid. The solution is provided by DDNS service. Similarly to DNS server, it provides a database containing relations between domain and numeric addresses, but this database may be updated on request by the domain owner. Thanks to this feature, the server is available in the domain address regardless its actual IP number. In such a case, the access to the server is limited to its domain name translated by DDNS server, unless we know its actual IP number (but of course we do not know how long it will be valid). We have to remember that when DHCP server changes the IP, it takes some time to detect this change by the client software or router, and, after the notification is sent to DDNS server, it takes another minute or so to send this piece of data to DNS server to update the database. In result, our server will be periodically unavailable up to several minutes, every time the IP address has been changed.

DDNS service is accessible via a number of providers. Its basic version, sufficient to support the above configuration, is usually free of charge. All devices supporting DDNS usually have several provider addresses preset by default.

About the author :Michal Lepiarz
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