Frequently Asked Question
Why the need for DDNS Services ?
Last Updated 9 years ago
Most internet subscriber in Singapore are subscribing to a Dynamic IP internet services. This mean that the Public IP the ISP assigned you will change occasionally. This Public IP is like a phone number. When you are connecting from the internet, you will need this Public IP address when you are outside to connect back to your CCTV System. However, there need to be a way to track it when it changes, otherwise imagine that you keep changing your phone number, your friends would not be able to reach you when they don't have your latest updated phone number.
When we do the setup, the DVR supports a DDNS (Dynamic DNS) client. This function will update a Hostname that we configure (e.g. mac000e53abcdef.ddns.dvrtw.com.tw, mycctvsystem.dvrdns.org, etc) with the latest IP address your ISP assigned you. Using this will enable you to keep track of the latest IP address your IP assigned you. Imagine you are on an online phonebook, your phone automatically update your entry with the latest phone number everytime you change phone number. Now, instead of having to inform your friend everytime you change phone number, your friend just need to sync their contact list with this online phonebook and dial your name everytime they want to reach you. This is what this services does.
Why am I still getting IP address not accessible then ?
Your internet router is the one that will know exactly when your ISP (Singnet, M1, Starhub, etc) changes your Public IP address. Any devices connected to your internet router will not know the exact moment. They can only check it occasionally to see if the Public IP had change and there's a need to update the hostname with your latest IP address. This interval may range from every couple of mins, or every couple of hours. It depends on how the manufacturer/software developer design the software/hardware.
So when the IP changes and BEFORE the hostname get updated with the latest IP address, there will be a mismatch of IP address until it get updated. Think of it as your phone did not update the online phonebook immediately when you change phone number, and it only update an hour later. Any friends who want to contact you within this hour will still be attempting to contact you at your old phone number and they won't be able to get through.
And due to the design of the internet and the multiple routes/caching at each stage, sometimes even when the IP address is updated, the client might still be caching the old IP address and won't be retrieving the new one for a while. Imagine it as your phone already automatically update the new phone number to the online phonebook, but your friend's phone won't be syncing for another hour. And during this time when your friend try to reach you, his phone is still using the old number. Another friend phone may be set to sync more frequently, and when that friend tried to call, he'll get you at your new number whereas the other friend would be still attempting to reach you at the old number. This is by design of internet. So there isn't much we can do. The only thing is to close the apps and try again. Restarting the apps will force the apps to clear the memory and get the latest IP from the DDNS server. Sometimes restarting of phone might be needed as the phone itself also might cache the IP, and the apps attempt to get the latest IP might be just retrieving it from the phone memory instead of actually retrieving it from the DDNS server. This is also the reason why most support personal would ask you to restart your devices and try again when things doesn't go right for any support issues.
How can I reduce or eliminate this issues ?
You can either get a router that support DDNS services and enable that function. This means that the internet router will be keeping track of your changing IP instead of the CCTV system. As the internet router is directly aware when the IP changes, the update will be faster. Singnet default router does not support the DDNS function. Most other ISP router does. You will have to check if the router manufacturer provide a free DDNS server (Dlink does), or you will have to subscribe to a paid one, e.g. http://www.dyndns.com
To totally eliminate the issue, you would have to change your internet subscription from a Dynamic IP Plan to a Static IP plan. Normally, a static ip plan will cost about 3 times the price of the dynamic ip plan. That's the reason why we rarely request customer to do so unless the CCTV system is so critical that they cannot do without access to the system remotely even for a short while.
Do note that the CCTV system is self contain. It doesn't require the internet for recording. The internet is only for remote monitoring. So even if you are unable to view from the internet, the system is still functioning and recording. You can always playback what you miss when the IP get updated.
When we do the setup, the DVR supports a DDNS (Dynamic DNS) client. This function will update a Hostname that we configure (e.g. mac000e53abcdef.ddns.dvrtw.com.tw, mycctvsystem.dvrdns.org, etc) with the latest IP address your ISP assigned you. Using this will enable you to keep track of the latest IP address your IP assigned you. Imagine you are on an online phonebook, your phone automatically update your entry with the latest phone number everytime you change phone number. Now, instead of having to inform your friend everytime you change phone number, your friend just need to sync their contact list with this online phonebook and dial your name everytime they want to reach you. This is what this services does.
Why am I still getting IP address not accessible then ?
Your internet router is the one that will know exactly when your ISP (Singnet, M1, Starhub, etc) changes your Public IP address. Any devices connected to your internet router will not know the exact moment. They can only check it occasionally to see if the Public IP had change and there's a need to update the hostname with your latest IP address. This interval may range from every couple of mins, or every couple of hours. It depends on how the manufacturer/software developer design the software/hardware.
So when the IP changes and BEFORE the hostname get updated with the latest IP address, there will be a mismatch of IP address until it get updated. Think of it as your phone did not update the online phonebook immediately when you change phone number, and it only update an hour later. Any friends who want to contact you within this hour will still be attempting to contact you at your old phone number and they won't be able to get through.
And due to the design of the internet and the multiple routes/caching at each stage, sometimes even when the IP address is updated, the client might still be caching the old IP address and won't be retrieving the new one for a while. Imagine it as your phone already automatically update the new phone number to the online phonebook, but your friend's phone won't be syncing for another hour. And during this time when your friend try to reach you, his phone is still using the old number. Another friend phone may be set to sync more frequently, and when that friend tried to call, he'll get you at your new number whereas the other friend would be still attempting to reach you at the old number. This is by design of internet. So there isn't much we can do. The only thing is to close the apps and try again. Restarting the apps will force the apps to clear the memory and get the latest IP from the DDNS server. Sometimes restarting of phone might be needed as the phone itself also might cache the IP, and the apps attempt to get the latest IP might be just retrieving it from the phone memory instead of actually retrieving it from the DDNS server. This is also the reason why most support personal would ask you to restart your devices and try again when things doesn't go right for any support issues.
How can I reduce or eliminate this issues ?
You can either get a router that support DDNS services and enable that function. This means that the internet router will be keeping track of your changing IP instead of the CCTV system. As the internet router is directly aware when the IP changes, the update will be faster. Singnet default router does not support the DDNS function. Most other ISP router does. You will have to check if the router manufacturer provide a free DDNS server (Dlink does), or you will have to subscribe to a paid one, e.g. http://www.dyndns.com
To totally eliminate the issue, you would have to change your internet subscription from a Dynamic IP Plan to a Static IP plan. Normally, a static ip plan will cost about 3 times the price of the dynamic ip plan. That's the reason why we rarely request customer to do so unless the CCTV system is so critical that they cannot do without access to the system remotely even for a short while.
Do note that the CCTV system is self contain. It doesn't require the internet for recording. The internet is only for remote monitoring. So even if you are unable to view from the internet, the system is still functioning and recording. You can always playback what you miss when the IP get updated.