For the zone in question run the following command:
dnscmd /zoneinfo foobar.com
You will get the result like this:
Zone query result:
ptr = 0000000000327C90
zone name = foobar.com
zone DN = DC=fopobar.com,cn=MicrosoftDNS,DC=DomainDnsZones,DC=foobar,DC=com Scavenge Servers
Server => af=2, salen=16, [sub=0, flag=00000000] p=13568, addr=192.168.1.1
Here you notice the IP address 192.168.1.1
This is the IP address of the only server which has the permission to scavenge the zone. Most likely this could be a server which is no longer existing - this happens a lot in Domains with a funktion level of 2008. If this is not the IP address of the server which on which you have configured Scavenging, you need to change that.
To change the Scavenging server for a zone, run the command:
dnscmd /zoneresetscavengeservers foobar.com <IP of the correct DNS Server>
And a few moments later, your DNS is working with Scavenging again.