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Forum Discussion

FFive's avatar
FFive
Icon for Altocumulus rankAltocumulus
Dec 17, 2021

DNS queries flapping between external and internal vIPs even if the source requests is internal.

I am trying to understand what could be causing this sort of behavior. In our environment we multiple domain controllers that delegate to the F5 GTM. We set up the GTM to respond to internal queries ...
application delivery
BIG-IP
BIG-IP DNS
Niels_van_Sluis's avatar
Niels_van_Sluis
Icon for MVP rankMVP
Dec 18, 2021

First make sure the virtual servers are limited to listen on either the external or internal VLANs. It sounds like a routing issue in your network. You can use tcpdump to see on what VLANs the requests are being received. The syntax below will also log the source MAC address.

 

tcpdump -enni 0.0:nnnp udp port 53