virtualbox.org

I have a WindowsXP virtual machine that uses anti-virus software that occasionally gets updated. I have a linked clone of this machine. If the base machine's anti-virus definitions are updated, does that update flow to the clone too, or does it need to update it's own definitions?

I'm asking because I don't use the VM very often, so when I do fire it up, it often needs some time to get new AV files and do a scan. I don't make significant changes to the linked clone, and it's so fast to make one that it's easier for me to delete and re-clone vs. updating the AV files on both machines.That is, unless I don't have to.

No, linked clones have a common ancestry but beyond that they are completely independant. The only thing that makes a linked clone different from a full clone, other than being faster to create, is their dependance on the base VDI remaining uncorrupted. Note than even the original VM no longer has the right to modify the base VDI. The original VM is now using a difference disk just like the linked clone(s), hence there is no way data can propagate from one VM to the next.