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I have a shiny new toy, a Cisco Wireless-N Gigabit Security Router with VPN (WRVS4400N). While looking through the instruction manual, I discovered that it had support for DynDNS built-in.

We've currently got the DynDNS client running on one of the servers (that people SSH to, as documented in this question); but the reason for the router update is to move away from SSH to VPN.

To that end, is there any difference in behaviour/functionality/maintainability to run it off the computer, as opposed to the router? Thus far, DynDNS has more or less a set-and-forget setup, but since the feature was there, I wanted to know if it was a better location for the process...

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4 Answers 4

up vote 2 down vote accepted

There are differences:

If implemented properly, the router will notify the ddns provider of your new ip address (1) if it has changed and (2) also optionally periodically.

When you have an ddns update script running on a machine on the LAN, unless it designed to work with some extra service on the WAN(not common), it will not know when the LANs public ip address changes. So it can only do periodic updates.

This means that if you have the ddns update script running every 10 minutes, and your ip address changes 1 minute after the last update, your ip address will not be set correctly for about 9 minutes.

So IMHO, it is better for it to running on the router.

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I work for DynDNS Support, so I will be glad to answer any questions you have.

In general, we have found the software clients in computers to be much more reliable compared to some router update clients. The reason for this is there are varying degrees of support for DynDNS in routers and other devices.

While these devices may claim to have DynDNS support, they sometimes are very buggy or not properly using our update API. This can cause issues such as abusive updates or maybe the update client not even being able to send us an update consistently. Abusive updates are the flooding our update servers with the same IP address every minute or so instead of only sending us an update when the IP address changes.

If the router's update client is written properly (which I do not know about the model you own), then it should work as well as your software update client. Only way to find

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2  
Interesting. Would be even better if you finished your last sentence. :) –  gravyface Jun 15 '10 at 13:13

DynDNS.com is one of the larger providers and benefits from widespread support for their update protocol in hardware devices. It's been around for a long time and is fairly well supported. I would expect a hardware update client from Cisco would be just as good as a software updater running on one of the computers would be. I'd try the hardware updater to see if it meets your needs and, if not, switch to a software updater. Hardware-based update clients for other services have support that is not as stable, so your mileage may vary if the provider is not DynDNS.com.

As an aside, I run DtDNS, a smaller dynamic DNS provider. There are a limited number of hardware devices that support my service, and I've found many of them to simply be broken. DynDNS.com has had much better luck in getting hardware vendors to support their service with update clients that actually work properly.

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Functionally, they are equivalent.

However, for maintainability, I would personally recommend setting it up on the router as it is something that you can set and forget in a sense. Your PC may need to be reformatted or it might just break-down at some point.

By setting it up on the router, you are abstracting and isolating your network settings away from your PC. You can replace the PC in the future with another PC and it still would not need to have the settings changed.

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not sure why this was modded down; he makes some good points. Plus, your router typically sees better uptime than a PC (particularly a Windows PC), unless you have a home server. –  gravyface Jun 15 '10 at 13:12
    
@gravyface I have a feeling it's because of the "they are equivalent" statement - the other respondents see a difference between them. –  Margaret Jun 15 '10 at 14:42
    
The accepted answer makes one big assumption, that is the router's ddns client makes changes when the public IP changes. Since I am an embedded guy, I don't make such assumptions because as far as I know, your router could be running behind a modem or that the ddns software is bugged. So, to me, both choices are equivalent. –  sybreon Jun 16 '10 at 1:08

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