Artificial intelligence (AI)-focused computer networking equipment manufacturer Arista Networks (ANET 17.47%) stock soared 15.7% through 10:10 a.m. Wednesday after the company beat soundly on earnings last night.

Heading into the company's Q2 report, analysts forecast Arista would earn $0.65 per share, adjusted for one-time items, on $2.1 billion in sales. In fact, Arista earned $0.73 per share and its sales were $2.2 billion.

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Arista's Q2 earnings

Revenue for the hardware maker surged 30% year over year, and gross profit margin improved about 30 basis points, to 65.2%. Adjusted earnings were fabulous, but Arista's performance wasn't too shabby even when calculated according to generally accepted accounting principles (GAAP).

Net profit for the quarter hit $0.70 per share, up 35%, as better margins on growing sales helped earnings growth to outpace sales growth.

Free cash flow for the year to date is now $1.79 billion, better than reported net income, and up 20% year over year.

Is Arista Networks stock a buy?

Arista predicted revenue will continue growing past $2.2 billion in Q3, but did not give specific guidance for earnings. Wall Street analysts on average have the company pegged for a $2.81-per-share profit this year, up 24% from last year.

If they're right about that, then Arista stock at 50 times earnings today is selling for a pretty aggressive 2 price/earnings-to-growth (PEG) ratio -- much more than I'd like to pay, and toward the high end of what seems to be normal in this current bull market. Still, Arista just proved in Q2 that it can grow faster than 24% -- to be precise, that it can grow 30% in a good quarter.

Priced at a 1.7 PEG ratio based on 30% growth, Arista stock may still have room to run.