Dynamic Domain Name System (DDNS) in Application Layer

When DNS (Domain Name System) was designed, nobody expected that there would be so many address changes such as adding a new host, removing a host, or changing an IP address. When there is a change, the change must be made to the DNS master file which needs a lot of manual updating and it must be updated dynamically.

Dynamic Domain Name System (DDNS):

It is a method of automatically updating a name server in the Domain Name Server (DNS), often in real-time, with the active DDNS configuration of its configured hostnames, addresses, or other information. In DDNS, when a binding between a name and an address is determined, the information is sent, usually by DHCP (Dynamic Host Configuration Protocol) to a primary DNS server.

The primary server updates the zone. The secondary servers are notified either actively or passively. Inactive notification, the primary server sends a message to secondary servers, whereas, in the passive notification, the secondary servers periodically check for any changes. In either case, after being notified about the change, the secondary requests information about the entire zone (zone transfer).

DDNS can use an authentication mechanism to provide security and prevent unauthorized changes in DNS records.

Advantages:

1. It saves time required by static addresses updates manually when network configuration changes.

2. It saves space as the number of addresses are used as required at one time rather than using one for all the possible users of the IP address.

3. It is very comfortable for users point of view as any IP address changes will not affect any of their activities.

4. It does not affect accessibility as changed IP addresses are configured automatically against URL’s.

Disadvantages:

1. It is less reliable due to lack of static IP addresses and domain name mappings.

2. Dynamic DNS services alone can not make any guarantee about the device you are attempting to connect is actually your own.

Uses:

1. It is used for Internet access devices such as routers.

2. It is used for for security appliance manufacturers and even required for IP-based security appliances like DVRs.