Improve/fix dynamic DNS for WAN/cellular failover


#1

There are quite a few older requests and bug reports about dynamic DNS. This needs to be addresses in a consolidated fashion.
FOr anyone not familiar with dynamic DNS, this is where you use a service such as dyndns.com to register host names like mypeplinkxx.dyndns-ip.org and this hostname always points to the current public IP of the pepwave, becasue every time the IP changes the pepwave updates the IP at dyndns.

The issue seems to be that engineering only considered dynamic dns for dynamic IPs on a WAN link. And of course it is used for that. But more frequently it is needed to update a dynamic host name when a pepwave switches to cellular and back.

It ALMOST works perfectly for this, and we have it set this way on about 40 pepwaves.

The only issue we have (and it is a real problem) is that sometimes the update seems to fail. the event log shows that it was updated, but dyndns still has the previous IP. I believe that this is a timing issue. One thing I have observed is that it ALWAYS seems to be when the unit switches from cellular back to WAN, but dyndns still shows the cellular IP.
This means that applications using that dynamic host name now fail until we notice that failure and manually correct the IP.
This happens perhaps once every few days to one unit or another.
Suggestion: The pepwave can test the hostname a minute after making the change. If it has not updated, send the update again. If it fails several times, perhaps that should be a notifiable event.


#2

I think you may find a better solution with us with Find My Peplink. Meanwhile, we will look into how to fix the dynamic IPs update on the dynamic DNS service.


#3

Find my peplink will not work at all for this, as it returns ALL wan IP addresses. i.e. you get the WAN and cellular address. What we really need is for the DDNS updates to function more solidly, so the ddns host name always returns the current active ip. As I indicated, it works that way maybe 99% of the time. But some updates from cell to WAN fail to properly apply.


#4

We will look into that and figure out the 1% chance of not updating correctly. Find My Peplink actually returns active WAN IP addresses only and those standby WAN are not included. If you want to look up the standby WAN IP by domain, you can do that with the per WAN domain. That is also given to you when you register your device with the Find My Peplink.


#5

That does not appear to be correct. here is output of a findmypeplink lookup. the 73.75.19.154 address is active, the 166.152.163.105 address is in standby
C:\Users\John Scully>nslookup 2932-d692-dca0.mypep.link
Server: google-public-dns-a.google.com
Address: 8.8.8.8

Non-authoritative answer:
Name: 2932-d692-dca0.mypep.link
Addresses: 166.152.163.105
73.75.19.154


#6

We just made an adjustment. The DDNS name now returns the IC2 detected IP only. Standby WANs’ IP will never be returned.

$ nslookup 2932-d692-dca0.mypep.link 8.8.8.8
Server: 8.8.8.8
Address: 8.8.8.8#53

Non-authoritative answer:
Name: 2932-d692-dca0.mypep.link
Address: 73.75.19.154


#7

#8