Left 4 Dead questions

1.On the Tool category of Steam accounts, there's an option that installs ''Left 4 Dead Dedicated Server'', what does it do exactly?2.If you were within the explosion zone of the bomber and it infected you, does it still count as a vomit which will also lures zombies?  Left 4 Dead questions
1: it installs a dedicated server client wich you can use to run a dedicated server

2: yes

3: there is a L4D forum better suited to this

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