in reply to Misunderstanding negative look behind

Untested speculation, but based purely upon reading your post, I'd guess that the problem is that this:

(?<!10\.20\.11\.99\s)kvm-test-v06

[download]

is anticipating exactly 1 whitespace char between the IP address and the name and perhaps some of your lines have more than one?

Does this: (?<!10\.20\.11\.99)\s+kvm-test-v06 more closely meet you needs?

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The start of some sanity?

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