What I need is to pull JUST the node key (which is variable based on how many servers are entered...could be node0-node199).   [emphases added]

From the quote from the OP and from the examples therein, I get the notion that the pattern is best described as "the literal 'node' at the start of a string, immediately followed by 1 to 3 (and no more) decimal digits". The regex  /(node[0-9]*)/ matches  'node' anywhere, followed by any number (including zero) of digits. IMHO, a better (because more specific) regex would be
    m{ \A (node \d{1,3}) (?! \d) }xms
(which has not been tested).