* Q4 adj EPS $0.10 vs est. $0.09
* Q4 revenue rises 45 percent, beats estimates
* Sees Q1 EPS, revenue above estimates
* Shares up 1 percent in extended trade (Adds analyst comment, conference call details)
BANGALORE, Aug 26 Aruba Networks Inc ARUN.O reported quarterly earnings above Wall Street estimates on strong revenue growth as it grabbed market share with its highest-ever quarterly customer additions.
However, concerns of higher expenses to support the expanding client base could limit future bottom line, say analysts.
The No. 2 wireless LAN provider after Cisco Systems Inc (CSCO.O) supplies equipment for secured wireless networks used in offices. The company's customers include Microsoft Corp (MSFT.O), NTT Data Corp (9613.T) and the U.S. Air Force, according to its latest annual report.
The strong revenue it posted indicated that the company was gaining market share against rivals such as Cisco and Meru Networks MERU.O.
Expenses rose as Aruba added headcount and equipment to cope with soaring demand in a quarter it added more than 900 customers.
Operating expenses at the Sunnyvale, California-based company rose 30 percent in the fourth quarter.
"It was an excellent quarter from a top-line perspective," Mizuho Securities USA analyst Joanna Makris said, who noted that expectations were running high ahead of the results.
"The bottom line is a concern. The question is, can they follow through on the bottom line," she said.
The one-cent profit beat was not proportionate with the magnitude of the revenue beat, Makris said. Revenue topped estimates by $3.8 million.
For the first quarter, the company forecast earnings per share of 11 cents, a penny above market expectations. It expects revenue of $79-$81 million, above Wall Street expectations of $77.8 million.
For the fourth quarter ended July 31, the company posted net income of $423,000, or break even per share, compared with a net loss of $4.5 million, or 5 cents a share, a year earlier. Excluding items, earnings were 10 cents a share.
Revenue rose 45 percent to $77.3 million. Product revenue grew 51 percent.
Analysts expected earnings of 9 cents a share on revenue of $73.5 million, according to Thomson Reuters I/B/E/S.
Shares of Aruba -- which also competes with Hewlett-Packard (HPQ.N) and Motorola MOT.N -- rose 1 percent to $16.81 in trading after the bell.
The stock, which has more than doubled in the last 52 weeks, closed at $16.57 Thursday on Nasdaq. (Reporting by S. John Tilak in Bangalore; Editing by Vyas Mohan)