I've an ongoing quarrell with the German company AVM which produces Fritz! routers: The router sometimes returns invalid/old addresses for network devices in a name resolution query. AVM keeps saying that any unmanaged switch in my network may have changed the returned address...
I think that this is complete nonsense, but anyway, I'd like to have a one-liner by Netgerar saying so in order to make AVM accept this.
Fully agree, complete nonsense. An unmanaged (and most managed switches in the usual configurations) are unable to change anyhting on a DNS query and it's reply.
For my curiosity, what types of hosts are affected by this problem? What kind of DNS entries are affected? For example domains or subdomains with short TTL (clusters, HA systems, ...), domains returning round roind ip addresses, local FritzBox LAN DNS names with host names based on the DHCP client provided information?
The problem is not related to a special type of device. Any device may be affeted, after its lease expired and its IP changed, AVM/Fritz! sometimes returns the old address. It's tedious to reproduce this problem so they put the blame on the switches in my network which "might have changed the address"...
So I'd like to have a one-line reply from a Netgear guy on this.
The problem is not related to a special type of device. Any device may be affeted, after its lease expired and its IP changed, AVM/Fritz! sometimes returns the old address.
So as expected, it's not a generic DNS issue - much more about the devices on your LAN where the DHCP server does not update the embedded DNS with the different IP issued. Not sure what AVM does implement these days - dnsmasq it used to be. All these features came essentially FREE with dnsmasq.
Oddly Netgear never added the automatic DNS feature for the LAN, they are stuck in 1995 specs - one of the reasons we deploy AVM and ZyXEL.
This is a little bit strange because at least the newer AVM routers I have in my management scope keep long lists of disconnected devices (don't know how long the list can be), and they will (on best effort - if not re-purposed because there are no more previously used free IPs) re-use the same IP address even after days or weeks. This might indicate there might be two components in place which don't communicate. Appears AVM firmware quality does go down to the bin, too. Reminds me somehow to Netgear's consumer router BU j**k (I'm not allowed to say here anymore).
A hint aside: For reliable services, I would suggest to make a MAC-IP address reservation also on the Fritz!box, so the same system will always get the same IP address assigned.
If some 11500 posts, 2100 kudos, and over 650 solutions posted qualify: Hey AVM, hallo Berlin - this DHCP/DNS issue can't be a switch problem. Just fix your router firmware. Free hints above... 8-)
