|        |
|--------|
|        |
|   |

|   |
|---|
|   |  |
| x | ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |

|        |
|--------|
|        |  |
|  ̈ | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |

|                                                               |
|---------------------------------------------------------------|
|                                                               |  |  |
| Delaware                                                      |   | 83-0380411 |
| (State or other jurisdiction ofincorporation or organization) |   | (I.R.S. EmployerIdentification Number) |

|                                |
|--------------------------------|
|                                |  |  |
| Title of each class            |   | Name of each exchange on which registered |
| Common Stock, $0.001 par value |   | New York Stock Exchange |

|                                   |
|-----------------------------------|
|                                   |  |  |  |
| Large accelerated filer |  ̈ | Accelerated filer | x |
| Non-accelerated filer             |  ̈  (Do not check if a smaller reporting company) | Smaller reporting company |  ̈ |

|        |
|--------|
|        |
|   |

----

----

|               |
|---------------|
|               |  |  |  |  |  |  |  |  |  |  |
| ExhibitNumber |   |   |   | Incorporated by Reference |
| Description   |   | Form |   | File No. |   | Exhibit |   | Filing Date |
| 2.1+          |   | Agreement and Plan of Merger by and among Intronis, Inc., Barracuda Networks, Inc., Igloo Merger Corp. and OpenView General Partner, L.P. as stockholder representative, dated as of September 23, 2015. |   | 8-K |   | 001-36162 |   | 2.1 |   | October 14, 2015 |
| 3.1           |   | Amended and Restated Certificate of Incorporation of the Registrant. |   | 10-Q |   | 001-36162 |   | 3.1 |   | January 13, 2014 |
| 3.2           |   | Amended and Restated Bylaws of the Registrant. |   | 10-Q |   | 001-36162 |   | 3.2 |   | January 13, 2014 |
| 4.1           |   | Amended and Restated Investors’ Rights Agreement dated as of October 3, 2012, between the registrant and the other parties thereto. |   | S-1 |   | 333-191510 |   | 4.1 |   | October 1, 2013 |
| 4.2           |   | Specimen common stock certificate of the registrant. |   | S-1/A |   | 333-191510 |   | 4.2 |   | October 11, 2013 |
| 4.3           |   | 2015 Employee Stock Purchase Plan and form of agreement thereunder. |   | S-8 |   | 333-206689 |   | 4.3 |   | August 31, 2015 |
| 10.1          |   | Form of Indemnification Agreement between the registrant and its directors and officers. |   | S-1 |   | 333-191510 |   | 10.1 |   | October 1, 2013 |
| 10.2          |   | 2004 Stock Option Plan, and form of agreements thereunder. |   | S-1 |   | 333-191510 |   | 10.2 |   | October 1, 2013 |
| 10.3          |   | 2012 Equity Incentive Plan, as amended, and form of agreements thereunder. |   | S-1/A |   | 333-191510 |   | 10.3 |   | October 23, 2013 |
| 10.4          |   | SignNow 2011 Equity Incentive Plan, form of agreements thereunder. |   | S-1 |   | 333-191510 |   | 10.4 |   | October 1, 2013 |
| 10.5          |   | Purewire, Inc. 2008 Stock Incentive Plan, form of agreements thereunder. |   | S-1 |   | 333-191510 |   | 10.5 |   | October 1, 2013 |
| 10.6          |   | Offer Letter, between the registrant and William D. Jenkins, Jr., dated June 7, 2013. |   | S-1 |   | 333-191510 |   | 10.6 |   | October 1, 2013 |
| 10.7          |   | Offer Letter, between the registrant and David Faugno, dated June 30, 2012. |   | S-1 |   | 333-191510 |   | 10.7 |   | October 1, 2013 |
| 10.8          |   | Offer Letter, between the registrant and Michael D. Perone, dated July 24, 2013. |   | S-1 |   | 333-191510 |   | 10.8 |   | October 1, 2013 |
| 10.9          |   | Offer Letter, between the registrant and Diane C. Honda, dated September 13, 2012. |   | S-1 |   | 333-191510 |   | 10.9 |   | October 1, 2013 |
| 10.10         |   | Offer Letter, between the registrant and Michael D. Hughes, dated August 25, 2012. |   | S-1 |   | 333-191510 |   | 10.10 |   | October 1, 2013 |
| 10.11         |   | Offer Letter, between the registrant and Zachary S. Levow, dated July 24, 2013. |   | S-1 |   | 333-191510 |   | 10.11 |   | October 1, 2013 |
| 10.12         |   | Purchase and Sale Agreement and Escrow Instructions dated as of July 31, 2011, between the registrant and Bryan Family Partnership II, Ltd. |   | S-1 |   | 333-191510 |   | 10.12 |   | October 1, 2013 |
| 10.13         |   | Credit Agreement dated as of October 3, 2012, between the registrant and Silicon Valley Bank. |   | S-1 |   | 333-191510 |   | 10.13 |   | October 1, 2013 |
| 10.14         |   | Lease dated as of June 19, 2013, between the registrant and M West Propco XVII, LLC. |   | S-1 |   | 333-191510 |   | 10.14 |   | October 1, 2013 |
| 10.15         |   | Lease dated as of May 24, 2012, between the registrant and 317 Maynard LLC. |   | S-1 |   | 333-191510 |   | 10.17 |   | October 1, 2013 |
| 10.16         |   | Summary of 2014 Executive Bonus Plan. |   | S-1/A |   | 333-191510 |   | 10.19 |   | October 11, 2013 |
| 10.17         |   | Second Amendment Agreement, dated as of January 23, 2015, between Barracuda Networks, Inc. and Silicon Valley Bank. |   | 8-K |   | 001-36162 |   | 10.1 |   | January 29, 2015 |

----

|               |
|---------------|
|               |  |  |  |  |  |  |  |  |  |  |
| ExhibitNumber |   |   |   | Incorporated by Reference |
| Description   |   | Form |   | File No. |   | Exhibit |   | Filing Date |
| 21.1*         |   | List of subsidiaries of registrant. |   |   |   |   |   |   |   |   |
| 23.1          |   | Consent of Ernst & Young LLP, Independent Registered Public Accounting Firm. |   |   |   |   |   |   |   |   |
| 31.1          |   | Certification of William D. Jenkins, Jr., Chief Executive Officer, pursuant to Rule 13a-14(a)/15d-14(a), as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |   |   |   |   |   |   |   |   |
| 31.2          |   | Certification of David Faugno, Chief Financial Officer, pursuant to Rule 13a-14(a)/15d-14(a), as adopted pursuant to Section 302 of the Sarbanes-Oxley Act of 2002. |   |   |   |   |   |   |   |   |
| 32.1**        |   | Certification of William D. Jenkins, Jr., Chief Executive Officer, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. |   |   |   |   |   |   |   |   |
| 32.2**        |   | Certification of David Faugno, Chief Financial Officer, pursuant to 18 U.S.C. Section 1350, as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002. |   |   |   |   |   |   |   |   |
| 101.INS*      |   | XBRL Instance Document. |   |   |   |   |   |   |   |   |
| 101.SCH*      |   | XBRL Taxonomy Extension Schema Document. |   |   |   |   |   |   |   |   |
| 101.CAL*      |   | XBRL Taxonomy Extension Calculation Linkbase Document. |   |   |   |   |   |   |   |   |
| 101.DEF*      |   | XBRL Taxonomy Extension Definition Linkbase Document. |   |   |   |   |   |   |   |   |
| 101.LAB*      |   | XBRL Taxonomy Extension Label Linkbase Document. |   |   |   |   |   |   |   |   |
| 101.PRE*      |   | XBRL Taxonomy Extension Presentation Linkbase Document. |   |   |   |   |   |   |   |   |

|        |
|--------|
|        |
|   |

|    |
|----|
|    |  |  |
| *  |   | Previously filed with our Annual Report on Form 10-K for the year ended February 29, 2016, as filed on May 4, 2016. |
| ** |   | Previously furnished with our Annual Report on Form 10-K for the year ended February 29, 2016, as filed on May 4, 2016. |

----

|        |
|--------|
|        |  |  |  |  |  |
|   |   |   | BARRACUDA NETWORKS, INC. |
|   |   |   |   |   |   |
|   |   |   | By: |   | /s/ William D. Jenkins, Jr. |
|   |   |   |   |   | William D. Jenkins, Jr. |
|   |   |   |   |   | Chief Executive Officer |

|                              |
|------------------------------|
|                              |  |  |  |  |
| Signature                    |    | Title |    | Date |
|                         |   |   |   |   |
| /s/ William D. Jenkins, Jr.  |    | Chief Executive Officer and Director |    | May 5, 2016 |
| William D. Jenkins, Jr. |   | (Principal Executive Officer) |   |   |
|                         |   |   |   |   |
| /s/ David Faugno             |    | Chief Financial Officer |    | May 5, 2016 |
| David Faugno                 |    | (Principal Financial Officer) |   |   |
|                         |   |   |   |   |
| /s/ Dustin Driggs            |    | Corporate Controller |    | May 5, 2016 |
| Dustin Driggs                |    | (Principal Accounting Officer) |   |   |
|                         |   |   |   |   |
| *                            |    | Lead Independent Director |    | May 5, 2016 |
| Jeffry R. Allen         |    |   |   |   |
|                         |   |   |   |   |
| *                            |    | Director |    | May 5, 2016 |
| James J. Goetz          |    |   |   |   |
|                         |   |   |   |   |
| *                            |    | Director |    | May 5, 2016 |
| David R. Golob          |   |   |   |   |
|                         |   |   |   |   |
| *                            |    | Director |    | May 5, 2016 |
| Zachary S. Levow             |   |   |   |   |
|                         |   |   |   |   |
| *                            |    | Director |    | May 5, 2016 |
| Michael D. Perone       |   |   |   |   |
|                         |   |   |   |   |
| *                            |    | Director |    | May 5, 2016 |
| Gordon L. Stitt         |   |   |   |   |
|                         |   |   |   |   |
| *                            |    | Director |    | May 5, 2016 |
| Kevin B. Thompson            |   |   |   |   |
|                         |   |   |   |   |

|        |
|--------|
|        |  |  |
| * By:  |   | /s/ William D. Jenkins, Jr. |
|   |   | William D. Jenkins, Jr. |
|   |   | Attorney-in-Fact |