What: Shares of Barracuda Networks, Inc. (NYSE:CUDA) plunged 20% as of 11:00 a.m. Friday after the company announced strong fiscal first quarter results, but followed with disappointing forward guidance.

So what: Quarterly revenue climbed 17.8% year over year to $78 million, including 13.9% growth in appliance revenue to $23.7 million, and a 19.6% increase in recurring subscription revenue to $54.3 million. Meanwhile, gross billings increased 7.6% (or 12% on a constant-currency basis) year over year to $94.3 million. Based on generally accepted accounting principles, that translated to a net loss of $3.8 million, or $0.07 per share. On a non-GAAP basis -- which means excluding items like stock-based compensation and acquisition expenses -- Barracuda Networks achieved net income of $5.1 million, or $0.09 per share.

Analysts, on average, were anticipating lower revenue and adjusted earnings of $77.3 million and $0.08 per share, respectively.

However, the market is less than pleased with the guidance management provided during the subsequent conference call with analysts. Despite the beat, Barracuda Networks anticipates current-quarter revenue $78 million to $79 million, and adjusted earnings of $0.09 per share. Analysts' models called for roughly the same earnings, but on higher revenue of $80.4 million. 

In addition for the full-fiscal-year, Barracuda Networks sees revenue of $325 million to $330 million, and adjusted earnings per share between $0.36 and $0.41. Here again, the mid-point of both ranges sits below Wall Street's expectations for full-year revenue of $328 million, and adjusted earnings of $0.39 per share.

Now what: To be fair, it's debatable whether Barracuda Networks' slight guidance shortfall is worthy of today's massive 20% drop in share price. But it also doesn't help that the company still isn't profitable on a GAAP basis, and investors' worries are further compounded by the fact Barracuda Networks has previously stated billings growth should be 16% to 18% for the full year. That's well above even the constant-currency billings growth it achieved in fiscal Q1, indicating an expected acceleration later in the year. For now, and as long as concerns surrounding that figure loom, I'm content watching Barracuda Networks stock from the sidelines.

Steve Symington has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.