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Exhibit 3.5

AMENDED AND RESTATED
BYLAWS
OF
FASTCLICK, INC.

ARTICLE I
Offices

        Section 1.1 Registered Office. The registered office of Fastclick, Inc. (the "Corporation") in the State of Delaware shall be at 1209 Orange Street, in the City of Wilmington, County of New Castle, and the name of the registered agent at that address shall be The Corporation Trust Company.

        Section 1.2 Principal Executive Office. The principal executive office of the Corporation shall be located at such place within or outside of the State of Delaware as the board of directors of the Corporation (the "Board of Directors") from time to time shall designate.

        Section 1.3 Other Offices. The Corporation may also have an office or offices at such other place or places either within or without of the State of Delaware, as the Board of Directors may from time to time determine or as the business of the Corporation may require.

ARTICLE II
Stockholders

        Section 2.1 Annual Meetings. An annual meeting of stockholders shall be held for the election of directors at such date, time and place, either within or without the State of Delaware, as may be designated by the Board of Directors from time to time. In the absence of any such designation, stockholders' meetings shall be at the principal executive office of the Corporation. Any other proper business may be transacted at the annual meeting.

        At an annual meeting of stockholders, only such business shall be conducted as shall have been properly brought before the meeting. To be properly brought before an annual meeting, business must be: (i) specified in the notice of meeting (or any supplement thereto) given by or at the direction of the Board of Directors, (ii) otherwise properly brought before the meeting by or at the direction of the Board of Directors, or (iii) otherwise properly brought before the meeting by a stockholder of record at the time of giving notice provided for in these Bylaws, who is entitled to vote at the meeting and who complies with the notice procedures set forth in this Section 2.1.

        For business to be properly brought before an annual meeting by a stockholder, the stockholder must have given timely notice thereof in writing to the Secretary of the Corporation. To be timely, a stockholder's notice must be delivered to or mailed and received at the principal executive offices of the Corporation not later than the close of business on the 90th day nor earlier than the close of business on the 120th day prior to the first anniversary of the preceding year's annual meeting; provided, however, that in the event that no annual meeting was held in the previous year or the date of the annual meeting is more than 30 days before or more than 60 days after the anniversary date of the previous year's annual meeting, notice by the stockholder to be timely must be so delivered or received not earlier than the close of business on the 120th day prior to the annual meeting and not later than the close of business on the later of (x) the 90th day prior to the annual meeting and (y) the 10th day following the date on which public announcement of the date of the annual meeting is first made. For purposes of this Section 2.1, a "public announcement" shall mean disclosure in a press release reported by the Dow Jones News Service, Associated Press or a comparable national news service or in a document publicly filed by the Corporation with the Securities and Exchange Commission. In no event

shall the public announcement of an adjournment of a stockholders meeting commence a new time period for the giving of a stockholder's notice as described above.

        A stockholder's notice to the Secretary of the Corporation shall set forth as to each matter the stockholder proposes to bring before the annual meeting: (1) a brief description of the business desired to be brought before the annual meeting and the reasons for conducting such business at the annual meeting, (2) the name and address, as they appear on the Corporation's books, of the stockholder proposing such business, (3) the class and number of shares of the Corporation which are beneficially owned by the stockholder, (4) any material interest of the stockholder in such business, and (5) any other information that is required to be provided by the stockholder pursuant to Regulation 14A under the Securities Exchange Act of 1934, as amended (the "Exchange Act"), in his capacity as a proponent to a stockholder proposal. Notwithstanding the foregoing, in order to include information with respect to a stockholder proposal in the proxy statement and form of proxy for an annual meeting of stockholders, stockholders must provide notice as required by the regulations promulgated under the Exchange Act. Nothing in this section shall be deemed to affect any rights of stockholders to request inclusion of proposals in the corporation's proxy statement pursuant to Rule 14a-8 under the Exchange Act.

        No business shall be conducted at any annual meeting except in accordance with the procedures set forth in this Section 2.1. The chairman of the annual meeting shall, if the facts warrant, determine and declare at the meeting that business was not properly brought before the meeting in accordance with the Bylaws, and, if he should so determine, he shall declare at the meeting that any such business not properly brought before the meeting shall not be transacted.

        Section 2.2 Special Meetings. Special meetings of stockholders may be called at any time only by the Board of Directors, the Chairman of the Board or the President. Special meetings may not be called by any other person or persons. Each special meeting shall be held at such date and time as is requested by the person or persons calling the meeting, within the limits fixed by law.

        At any special meeting of stockholders, only such business shall be conducted as shall have been properly brought before the meeting. To be properly brought before a special meeting of stockholders, business must be: (i) specified in the notice of such special meeting (or any supplement thereto) given by or at the direction of the Board of Directors or (ii) otherwise properly brought before the meeting by or at the direction of the Board of Directors.

        Section 2.3 Notice of Meetings. Whenever stockholders are required or permitted to take any action at a meeting, a written notice of the meeting shall be given which shall state the place, date and hour of the meeting, and, in the case of a special meeting, the purpose or purposes for which the meeting is called. Unless otherwise provided by law, the written notice of any meeting shall be given not less than 10 nor more than 60 days before the date of the meeting to each stockholder entitled to vote at such meeting. If mailed, such notice shall be deemed to be given when deposited in the United States mail, postage prepaid, directed to the stockholder at his address as it appears on the records of the Corporation.

        Section 2.4 Adjournments. Any meeting of stockholders, annual or special, may adjourn from time to time to reconvene at the same or some other place and notice need not be given of any such adjourned meeting if the time and place thereof are announced at the meeting at which the adjournment is taken. At the adjourned meeting, the Corporation may transact any business which might have been transacted at the original meeting. If the adjournment is for more than 30 days, or if after the adjournment a new record date is fixed for the adjourned meeting, a notice of the adjourned meeting shall be given to each stockholder of record entitled to vote at the meeting.

        Section 2.5 Quorum. At each meeting of stockholders, except where otherwise provided by law, the Corporation's certificate of incorporation (the "Certificate of Incorporation") or these Bylaws, the

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holders of a majority of the outstanding shares of each class of stock entitled to vote at the meeting, present in person or represented by proxy, shall constitute a quorum. For purposes of the foregoing, two or more classes or series of stock shall be considered a single class if the holders thereof are entitled to vote together as a single class at the meeting. In the absence of a quorum, the stockholders so present may, by majority vote, adjourn the meeting from time to time in the manner provided by Section 2.4 of these Bylaws until a quorum shall attend. Shares of its own capital stock belonging, on the record date for the meeting, to the Corporation or to another corporation, if a majority of the shares entitled to vote in the election of directors of such other corporation is held, directly or indirectly, by the Corporation, shall neither be entitled to vote nor be counted for quorum purposes; provided, however, that the foregoing shall not limit the right of the Corporation to vote stock, including, but not limited to, its own stock, held by it in a fiduciary capacity.

        Section 2.6 Organization. Meetings of stockholders shall be presided over by the Chairman of the Board of Directors, if any, or in his absence, by the President, or in his absence, by a Vice President, or in the absence of the foregoing persons, by a chairman designated by the Board of Directors, or in the absence of such designation, by a chairman chosen at the meeting. The Secretary shall act as secretary of the meeting, but in his absence the chairman of the meeting may appoint any person to act as secretary of the meeting.

        The Board of Directors shall be entitled to make such rules or regulations for the conduct of meetings of stockholders as it shall deem necessary, appropriate or convenient. Subject to such rules and regulations of the Board of Directors, if any, the chairman of the meeting shall have the right and authority to prescribe such rules, regulations and procedures and to do all such acts as, in the judgment of the chairman, are necessary, appropriate or convenient for the proper conduct of the meeting, including, without limitation, establishing an agenda or order of business for the meeting, rules and procedures for maintaining order at the meeting and the safety of those present, limitations on participation in such meeting to stockholders of record of the Corporation and their duly authorized and constituted proxies, and such other persons as the chairman shall permit, restrictions on entry to the meeting after the time fixed for the commencement thereof, limitations on the time allotted to questions or comments by participants and regulation of the opening and closing of the polls for balloting and matters which are to be voted on by ballot. Unless and to the extent determined by the Board of Directors or the chairman of the meeting, meetings of stockholders shall not be required to be held in accordance with rules of parliamentary procedure.

        Section 2.7 Voting; Proxies. Unless otherwise provided in the Certificate of Incorporation, each stockholder entitled to vote at any meeting of stockholders shall be entitled to one vote for each share of stock held by him which has voting power upon the matter in question. If the Certificate of Incorporation provides for more or less than one vote for any share on any matter, every reference in these Bylaws to a majority or other proportion of stock shall refer to such majority or other proportion of the votes of such stock. A stockholder may vote the shares owned of record by him either in person or by proxy executed in writing (which shall include writings sent by telex, telegraph, cable, facsimile transmission or other means of electronic transmission) by the stockholder himself or his duly authorized attorney-in-fact; provided, however, that any such telex, telegram, cablegram, facsimile transmission or other means of electronic transmission must either set forth or be submitted with information from which it can be determined that the telex, telegram, cablegram, facsimile transmission or other means of electronic transmission was authorized by the stockholder. If it is determined that such telexes, telegrams, cablegrams, facsimile transmissions or other electronic transmissions are valid, the inspectors or, if there are no inspectors, such other persons making that determination shall specify the information upon which they relied. Any copy, facsimile telecommunication or other reliable reproduction of the writing or transmission created pursuant to the foregoing sentences of this Section 2.7 may be substituted or used in lieu of the original writing or transmission for any and all purposes for which the original writing or transmission could be used, provided that such copy, facsimile

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telecommunication or other reproduction shall be a complete reproduction of the entire original writing or transmission. Execution of the proxy may be accomplished by the stockholder or his authorized officer, director, employee or agent signing such writing or causing his or her signature to be affixed to such writing by any reasonable means including, but not limited to, by facsimile signature. No such proxy shall be voted or acted upon after three years from its date, unless the proxy provides for a longer period. A duly executed proxy shall be irrevocable if it states that it is irrevocable and if, and only as long as, it is coupled with an interest sufficient in law to support an irrevocable power. A stockholder may revoke any proxy which is not irrevocable by attending the meeting and voting in person or by filing an instrument in writing revoking the proxy or another duly executed proxy bearing a later date with the Secretary of the Corporation, Voting at meetings of stockholders need not be by written ballot and need not be conducted by inspectors, unless required by Section 2.10 of these Bylaws, or unless the holders of a majority of the outstanding shares of all classes of stock entitled to vote thereon present in person or by proxy at such meeting shall so determine. At all meetings of stockholders for the election of directors or otherwise, all elections and questions shall, unless otherwise provided by law, by the Certificate of Incorporation or these Bylaws, be decided by the vote of the holders of a majority of the outstanding shares of all classes of stock entitled to vote thereon present in person or by proxy at the meeting.

        Section 2.8 Fixing Date for Determination of Stockholders of Record. In order that the Corporation may determine the stockholders entitled to notice of, or to vote at, any meeting of stockholders or any adjournment thereof, or entitled to receive payment of any dividend or other distribution or allotment of any rights, or entitled to exercise any rights in respect of any change, conversion or exchange of stock or for the purpose of any other lawful action, the Board of Directors may fix, in advance, a record date, which shall not be more than 60 nor less than 10 days before the date of such meeting, or more than 60 days prior to any other action. If no record date is fixed: (a) the record date for determining stockholders entitled to notice of, or to vote at a meeting of stockholders shall be at the close of business on the day next preceding the day on which notice is given, or, if notice is waived, at the close of business on the day next preceding the day on which the meeting is held; and (b) the record date for determining stockholders for any other purpose shall be at the close of business on the day on which the Board of Directors adopts the resolution relating thereto. A determination of stockholders of record entitled to notice of or to vote at a meeting of stockholders shall apply to any adjournment of the meeting; provided, however, that the Board of Directors may fix a new record date for the adjourned meeting.

        Section 2.9 List of Stockholders Entitled to Vote. The Secretary shall prepare and make, at least 10 days before every meeting of stockholders, a complete list of the stockholders entitled to vote at the meeting, arranged in alphabetical order, and showing the address of each stockholder and the number of shares registered in the name of each stockholder. Such list shall be open to the examination of any stockholder for any purpose germane to the meeting during ordinary business hours for a period of at least 10 days prior to the meeting, either at a place within the city where the meeting is to be held, which place shall be specified in the notice of the meeting, or, if not so specified, at the place where the meeting is to be held. The list shall also be produced and kept at the time and place of the meeting during the whole time thereof and may be inspected by any stockholder who is present.

        Section 2.10 Inspectors of Election. The Board of Directors shall, in advance of any meeting of stockholders, appoint one or more inspectors other than nominees for office to act at the meeting. The number of inspectors shall be either one or three. If inspectors are appointed at a meeting on the request of one or more stockholders or proxies, the holders of a majority of shares or other proxies present at the meeting shall determine whether one or three inspectors are to be appointed. If any person appointed as inspector fails to appear or fails or refuses to act, the vacancy may be filled by appointment by the Board of Directors before the meeting, or by the meeting chairman at the meeting.

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Each inspector, before entering upon the discharge of his duties, shall take and sign an oath to execute faithfully the duties of inspector with strict impartiality and according to the best of his ability.

        The duties of these inspectors shall be as follows: (i) ascertain the number of shares outstanding and the voting power of each; (ii) determine the shares represented at a meeting and the validity of proxies and ballots; (iii) count all votes and ballots; (iv) determine and retain for a reasonable period a record of the disposition of any challenges made to any determination by the inspectors; and (v) certify their determination of the number of shares represented at the meeting, and their count of all votes and ballots. The inspectors may appoint or retain other persons or entities to assist the inspectors in the performance of the duties of the inspectors.

        The date and time of the opening and the closing of the polls for each matter upon which the stockholders will vote at a meeting shall be announced at the meeting. No ballot, proxies or votes, nor any revocations thereof or changes thereto shall be accepted by the inspectors after the closing of the polls.

        Except as otherwise required by applicable law, in determining the validity and counting of proxies and ballots, the inspectors shall be limited to an examination of the proxies, any envelopes submitted with those proxies, any information provided in accordance with Section 2.7 hereof, ballots and the regular books and records of the Corporation.

        If there are three inspectors of election, the decision, act or certificate of a majority is effective in all respects as the decision, act or certificate of all. Any report or certificate made by the inspectors of election is prima facie evidence of the facts stated therein.

        Section 2.11 No Consent of Stockholders in Lieu of Meeting. Subject to the rights of the holders of any series of Preferred Stock or any class or series of stock having a preference over the Common Stock as to dividends or upon dissolution, liquidation or winding up, any action required or permitted to be taken by the stockholders of the Corporation must be effected at an annual or special meeting of stockholders of the Corporation, upon due notice and in accordance with the provisions of these Bylaws, and may not be effected by any consent in writing by such stockholders.

ARTICLE III
Board of Directors

        Section 3.1 Powers. The business and affairs of the Corporation shall be managed by or under the direction of the Board of Directors, except as may be otherwise provided by law or in the Certificate of Incorporation.

        Section 3.2 Number of Directors. The number of directors which shall constitute the whole Board of Directors shall be not less than three (3) nor more than nine (9) and will be fixed from time to time pursuant to a resolution adopted by the Board of Directors; provided, that no decrease in the number of directors shall shorten the term of any incumbent director. Directors need not be stockholders of the Corporation.

        Section 3.3 Election and Term of Office. Each director shall hold office until the annual meeting of stockholders held in the year in which his term of office expires and until his successor is duly elected and qualified.

        Section 3.4 Advance Notice of Stockholder Nominees. Only persons who are nominated in accordance with the procedures set forth in this Section 3.4 shall be eligible for election as directors. Nominations of persons for election to the Board of Directors of the Corporation may be made at a meeting of stockholders by or at the direction of the Board of Directors or by any stockholder of the Corporation entitled to vote for the election of directors at the meeting who complies with the notice procedures set forth in this Section 3.4. Such nominations, other than those made by or at the direction

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of the Board of Directors, shall be made pursuant to timely notice in writing to the Secretary of the Corporation.

        To be timely, a stockholder's notice must be delivered to or mailed and received at the principal executive offices of the Corporation not later than the close of business on the 90th day nor earlier than the close of business on the 120th day prior to the first anniversary of the preceding year's annual meeting; provided, however, that in the event that no annual meeting was held in the previous year or the date of the annual meeting is more than 30 days before or more than 60 days after the anniversary date of the previous year's annual meeting, notice by the stockholder to be timely must be so delivered or received not earlier than the close of business on the 120th day prior to the annual meeting and not later than the close of business on the later of (x) the 90th day prior to the annual meeting and (y) the 10th day following the date on which public announcement (as defined in Section 2.1 above) of the date of the annual meeting is first made. In no event shall the public announcement of an adjournment of a stockholders meeting commence a new time period for the giving of a stockholder's notice as described above.

        Such stockholder's notice shall set forth: (a) the name and address, as they appear on the Corporation's books, of the stockholder who intends to make the nomination and the name and address of the person or persons to be nominated; (b) the class or series and number of shares of the Corporation which are beneficially owned by the stockholder; (c) a representation that the stockholder is a holder of record of stock of the Corporation entitled to vote in the election of directors and intends to appear in person or by proxy at the meeting to nominate the person or persons specified in the notice; (d) a description of all arrangements or understandings between the stockholder and each nominee and any other person or persons (naming such person or persons) pursuant to which the nomination or nominations are to be made by the stockholder; (e) such other information regarding each nominee proposed by such stockholder as would have been required to be included in a proxy statement filed pursuant to Regulation 14A under the Exchange Act had each nominee been nominated, or intended to be nominated, by the Board of Directors; (f) the executed written consent of each nominee to serve as a director of the Corporation if so elected; and (g) if the stockholder intends to solicit proxies in support of such stockholder's nominee(s), a representation to that effect.

        No person shall be eligible for election as a director of the Corporation unless nominated in accordance with the procedures set forth in this Section 3.4. The chairman of the meeting shall, if the facts warrant, determine and declare at the meeting that a nomination was not made in accordance with the procedures prescribed by the Bylaws, and, if he should so determine, he shall so declare at the meeting and the defective nomination shall be disregarded.

        Section 3.5 Vacancies and Additional Directorships. Newly created directorships resulting from any increase in the number of directors and any vacancies on the Board of Directors resulting from death, resignation, disqualification, removal or other cause shall be filled solely by the Board of Directors, and not by the stockholders, by the affirmative vote of a majority of the remaining directors then in office, even though such majority is less than a quorum of the Board of Directors, or by a sole remaining director or as otherwise determined by the Board of Directors. Any director elected in accordance with the preceding sentence shall hold office until he next election of the class for which such director shall have been chosen and until his or her successor shall have been duly elected and qualified.

        Section 3.6 Regular Meetings. Regular meetings of the Board of Directors may be held at such places within or without the State of Delaware and at such times as the Board of Directors may from time to time determine and, if so determined, notice thereof need not be given.

        Section 3.7 Special Meetings. Special meetings of the Board of Directors may be held at any time or place within or without the State of Delaware whenever called by the Chairman of the Board, if any, by the President, or by any director. Reasonable notice thereof shall be given by the person or persons calling the meeting.

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        Section 3.8 Telephonic Meetings Permitted. Members of the Board of Directors, or any committee thereof, as the case may be, may participate in a meeting of the Board of Directors or such committee by means of conference telephone or similar communications equipment by means of which all persons participating in the meeting can hear each other, and participation in a meeting pursuant to this Bylaw shall constitute presence in person at such meeting.

        Section 3.9 Quorum; Vote Required for Action. At all meetings of the Board of Directors, a majority of the entire Board of Directors shall constitute a quorum for the transaction of business. The vote of a majority of the directors present at a meeting at which a quorum is present shall be the act of the Board of Directors unless the Certificate of Incorporation or these Bylaws shall require a vote of a greater number. In case at any meeting of the Board of Directors a quorum shall not be present, the members of the Board of Directors present may adjourn the meeting from time to time until a quorum shall attend.

        Section 3.10 Organization. Meetings of the Board of Directors shall be presided over by the Chairman of the Board of Directors, if any, or in his absence by the President, or in their absence by a chairman chosen at the meeting the Secretary of the Corporation shall act as secretary of the meeting, but in his absence the chairman of the meeting may appoint any person to act as secretary of the meeting.

        Section 3.11 Action by Directors Without a Meeting. Unless otherwise restricted by the Certificate of Incorporation or these Bylaws, any action required or permitted to be taken at any meeting of the Board of Directors, or of any committee thereof, may be taken without a meeting if all members of the Board of Directors or of such committee, as the case may be, consent thereto in writing, and the writing or writings are filed with the minutes of proceedings of the Board of Directors or committee.

        Section 3.12 Compensation of Directors. The Board of Directors shall have the authority to fix the compensation of directors.

        Section 3.13 Removal. Any director may be removed from office at any time, but only for cause, by the affirmative vote of the stockholders having a majority of the combined voting power of the then outstanding shares of all classes and series of capital stock of the Corporation entitled to vote in the election of directors of the Corporation, voting together as a single class.

ARTICLE IV
Committees

        Section 4.1 Committees. The Board of Directors may, by resolution passed by a majority of the Board of Directors, designate one or more committees, each committee to consist of one or more of the directors of the Corporation. The Board of Directors may designate one or more directors as alternate members of any committee who may replace any absent or disqualified member at any meeting of the committee. In the absence or disqualification of a member of a committee, the member or members thereof present at any meeting and not disqualified from voting, whether or not he or they constitute a quorum, may unanimously appoint another member of the Board of Directors to act at the meeting in place of any such absent or disqualified member. Any such committee, to the extent provided in the resolution of the Board of Directors, shall have and may exercise all the powers and authority of the Board of Directors in the management of the business and affairs of the Corporation and may authorize the seal of the Corporation to be affixed to all papers which may require it; but no such committee shall have power or authority in reference to amending the Certificate of Incorporation, adopting an agreement of merger or consolidation, recommending to the stockholders the sale, lease or exchange of all or substantially all of the Corporation's property and assets, recommending to the stockholders a dissolution of the Corporation or a revocation of dissolution, removing or indemnifying directors or amending these Bylaws; and, unless the resolution expressly so

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provides, no such committee shall have the power or authority to declare a dividend or to authorize the issuance of stock.

        Section 4.2 Committee Rules. Unless the Board of Directors otherwise provides, each committee designated by the Board of Directors may adopt, amend and repeal rules for the conduct of its business. In the absence of a provision by the Board of Directors or a provision in the rules of such committee to the contrary, a majority of the entire authorized number of members of such committee shall constitute a quorum for the transaction of business, the vote of a majority of the members present at a meeting at the time of such vote if a quorum is then present shall be the act of such committee, and in other respects each committee shall conduct its business in the same manner as the Board of Directors conducts its business pursuant to Article III of these Bylaws.

ARTICLE V
Officers

        Section 5.1 Officers; Election. As soon as practicable after the annual meeting of stockholders in each year, the Board of Directors shall elect a President or Chief Executive Officer, a Treasurer or Chief Financial Officer, and a Secretary, and it may, if it so determines, elect from among its members a Chairman of the Board. The Board of Directors may also elect one or more Executive Vice Presidents, one or more Vice Presidents, one or more Assistant Secretaries and one or more Assistant Treasurers or Assistant Chief Financial Officers and may give any of them such further designations or alternate titles as it considers desirable. Any number of offices may be held by the same person.

        Section 5.2 Term of Office; Resignation; Removal; Vacancies. Except as otherwise provided in a resolution of the Board of Directors electing any officer, each officer shall hold office until the first meeting of the Board of Directors after the annual meeting of stockholders next succeeding his election, and until his successor is elected and qualified or until his earlier death, resignation or removal. Any officer may resign at any time upon written notice to the Board of Directors or to the President or the Secretary of the Corporation. Such resignation shall take effect at the time specified therein, and unless otherwise specified therein no acceptance of such resignation shall be necessary to make it effective. The Board of Directors may remove any officer with or without cause at any time. Any such removal shall be without prejudice to the contractual rights of such officer, if any, with the Corporation, but the election of an officer shall not of itself create contractual rights. Any vacancy occurring in any office of the Corporation by death, resignation, removal or otherwise may be filled for the unexpired portion of the term by the Board of Directors at any regular or special meeting.

        Section 5.3 Powers and Duties. The officers of the Corporation shall have such powers and duties in the management of the Corporation as shall be stated in these Bylaws or in a resolution of the Board of Directors which is not inconsistent with these Bylaws and, to the extent not so stated, as generally pertain to their respective offices, subject to the, control of the Board of Directors. The Secretary shall have the duty to record the proceedings of the meetings of stockholders, the Board of Directors and any committees in a book to be kept for that purpose and shall have custody of the corporate seal of the Corporation with the authority to affix such seal to any instrument requiring it. The Board of Directors may require any officer, agent or employee to give security for the faithful performance of his duties.

ARTICLE VI
Indemnification of Directors, Officers,
Employees and Other Corporate Agents

        Section 6.1 Indemnification of Directors and Officers. The Corporation shall indemnify, in the manner and to the fullest extent permitted by the Delaware General Corporation Law, any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action,

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suit or proceeding, whether civil, criminal, administrative or investigative, by reason of the fact that he is or was a director or officer of the Corporation, or is or was serving at the request of the Corporation as a director or officer of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorneys' fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by him in connection with such action, suit or proceeding.

        Section 6.2 Indemnification of Others. The Corporation may indemnify, in the manner and to the fullest extent permitted by the Delaware General Corporation Law, any person who was or is a party or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative, by reason of the fact that he is or was an employee or agent of the Corporation, or is or was serving at the request of the Corporation as an employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against expenses (including attorneys' fees), judgments, fines and amounts paid in settlement actually and reasonably incurred by him in connection with such action, suit or proceeding.

        Section 6.3 Advance of Expenses. Costs and expenses (including attorneys' fees) incurred in defending any action or proceeding for which indemnification is required pursuant to Section 6.1 or for which indemnification is permitted pursuant to Section 6.2 may be paid by the Corporation in advance of the final disposition of such matter, if the indemnified party undertakes in writing to repay any such advances in the event that it is ultimately determined that he is not entitled to indemnification.

        Section 6.4 Non-Exclusivity. The right of indemnity and advancement of expenses provided herein shall not be deemed exclusive of any other rights to which any person seeking indemnification or advancement of expenses from the Corporation may be entitled under any agreement, vote of stockholders or disinterested directors or otherwise, both as to action in his official capacity and as to action in another capacity while holding such office. Any agreement for indemnification of or advancement of expenses to any director, officer, employee or agent or other person may provide rights of indemnification or advancement of expenses which are broader or otherwise different from those set forth herein.

        Section 6.5 Insurance. The Corporation may purchase and maintain insurance on behalf of any person who is or was a director, officer, employee or agent of the Corporation, or is or was serving at the request of the Corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise or as a member of any committee or similar body against any liability asserted against him and incurred by him in any such capacity, or arising out of his status as such, whether or nor the Corporation would have the power to indemnify him against such liability under the provisions of this Article VI or applicable law.

        Section 6.6 Inclusion of Constituent Corporation. For purposes of this Article VI, references to "the Corporation" shall include, in addition to the resulting corporation, any constituent corporation (including any constituent of a constituent) absorbed in a consolidation or merger which, if its separate existence had continued, would have had the power and authority to indemnify its directors, officers, employees and agents, so that any person who is or was a director, officer, employee or agent of such constituent corporation, or is or was serving at the request of such constituent corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, shall stand in the same position under the provisions of this Article VI with respect to the resulting or surviving corporation as he would have with respect to such constituent corporation if its separate existence had continued.

        Section 6.7 Inclusion of Other Terms. For purposes of this Article VI, reference to "other enterprises" shall include employee benefit plans; references to "fines" shall include any excise taxes assessed on a person with respect to any employee benefit plan; and references to "serving at the request of the Corporation" shall include any services as a director, officer, employee or agent of the

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Corporation which imposes duties on, or involves services by, such director, officer, employee or agent with respect to any employee benefit plan, its participants, or beneficiaries.

        Section 6.8 Continuation of Indemnification. The indemnification and advancement of expenses provided by, or granted pursuant to, this Article VI may, unless otherwise provided when authorized or ratified, continue as to a person who has ceased to be a director, officer, employee or agent and may inure to the benefit of the heirs, executors and administrators of such a person.

        Section 6.9 Amendments. Any repeal or modification of this Article VI shall only be prospective and shall not affect the rights under this Article VI in effect at the time of the alleged occurrence of any action or omission to act that is the cause of any proceeding against any director, officer, employee or agent of the Corporation.

ARTICLE VII
Stock

        Section 7.1 Certificates. Every holder of stock in the Corporation shall be entitled to have a certificate signed by or in the name of the Corporation by the Chairman of the Board, if any, or the Chief Executive Officer, or the President, or a Vice President, and by the Treasurer or Chief Financial Officer or an Assistant Treasurer or Assistant Chief Financial Officer, if any, or the Secretary or an Assistant Secretary, of the Corporation, certifying the number of shares owned by him in the Corporation. Any or all signatures on the certificate may be a facsimile. In case any officer, transfer agent or registrar who has signed or whose facsimile signature has been placed upon a certificate shall have ceased to be such officer, transfer agent or registrar before such certificate is issued, it may be issued by the Corporation with the same effect as if be were such officer, transfer agent or registrar at the date of issue.

        Section 7.2 Lost, Stolen or Destroyed Stock Certificates; Issuance of New Certificates. The Corporation may issue a new certificate of stock in the place of any certificate theretofore issued by it, alleged to have been lost, stolen or destroyed, and the Corporation may require the owner of the lost, stolen or destroyed certificate, or his legal representative, to give the Corporation a bond sufficient to indemnify it against any claim that may be made against it on account of the alleged loss, theft or destruction of any such certificate or the issuance of such new certificate.

ARTICLE VIII
Miscellaneous

        Section 8.1 Fiscal Year. The fiscal year of the Corporation shall be determined by the Board of Directors.

        Section 8.2 Seal. The Corporation may have a corporate seal which shall have the name of the Corporation inscribed thereon and shall be in such form as may be approved from time to time by the Board of Directors. The corporate seal may be used by causing it or a facsimile thereof to be impressed or affixed or in any other manner reproduced.

        Section 8.3 Waiver of Notice of Meetings of Stockholders, Directors and Committees. Whenever notice is required to be given by law or under any provision of the Certificate of Incorporation or these Bylaws, a written waiver thereof, signed by the person entitled to notice, whether before or after the time stated therein, shall be deemed equivalent to notice. Attendance of a person at a meeting shall constitute a waiver of notice of such meeting, except when the person attends a meeting for the express purpose of objecting, at the beginning of the meeting, to the transaction of any business because the meeting is not lawfully called or convened. Neither the business to be transacted at, nor the purpose of, any regular or special meeting of the stockholders, directors, or members of a committee of directors need be specified in any written waiver of notice unless so required by the Certificate of Incorporation

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or these Bylaws. Unless either proper notice of a meeting of the Board of Directors, or any committee thereof, has been given or else the persons entitled thereto have waived such notice (either in writing or by attendance as set forth above), any business transacted at such meeting shall be null and void.

        Section 8.4 Interested Directors; Quorum. No contract or transaction between the Corporation and one or more of its directors or officers, or between the Corporation and any other corporation, partnership, association or other organization in which one or more of its directors or officers are directors or officers or have a financial interest, shall be void or voidable solely for this reason, or solely because the director or officer is present at or participates in the meeting of the Board of Directors or committee thereof which authorizes the contract or transaction, or solely because his or their votes are counted for such purpose, if: (a) the material facts as to his relationship or interest and as to the contract or transaction are disclosed or are known to the Board of Directors or the committee, and the Board of Directors or committee in good faith authorizes the contract or transaction by the affirmative vote of a majority of the disinterested directors, even though the disinterested directors be less than a quorum, (b) the material facts as to his relationship or interest and as to the contract or transaction are disclosed or are known to the stockholders entitled to vote thereon, and the contract or transaction is specifically approved in good faith by vote of the stockholders or (c) the contract or transaction is fair as to the Corporation as of the time it is authorized, approved or ratified, by the Board of Directors, a committee thereof or the stockholders. Common or interested directors may be counted in determining the presence of a quorum at a meeting of the Board of Directors or of a committee which authorizes the contract or transaction.

        Section 8.5 Form of Records. Any records maintained by the Corporation in the regular course of its business, including its stock ledger, books of account and minute books, may be kept on, or be in the form of, punch cards, magnetic tape, photographs, microphotographs or any other information storage device, provided that the records so kept can be converted into clearly legible form within a reasonable time. The Corporation shall so convert any records so kept upon the request of any person entitled to inspect the same.

        Section 8.6 Gender. Any reference to the masculine gender in these Bylaws shall be construed to mean the feminine gender, as the situation may demand.

ARTICLE IX
Amendment of Bylaws

        Subject to Section 6.9 hereof and the laws of the State of Delaware, these Bylaws may be amended, altered or repealed and new Bylaws may be adopted (1) by the stockholders of the Corporation at any annual or special meeting of stockholders by the affirmative vote of the stockholders having a majority of the combined voting power of the then outstanding shares of all classes and series of capital stock of the Corporation entitled to vote at such meeting, voting together as a single class, or (2) by the affirmative vote of a majority of the entire Board of Directors, provided, however, that in each case any proposed amendment, alteration or repeal of, or the adoption of any provision inconsistent with, Article II, III or IX of these Bylaws shall require the affirmative vote of the holders of at least two-thirds of the combined voting power of the then outstanding shares of all classes and series of capital stock of the Corporation entitled to vote at any annual or special meeting of stockholders called for such purpose, voting together as a single class.

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QuickLinks

Exhibit 3.5

AMENDED AND RESTATED BYLAWS OF FASTCLICK, INC.
ARTICLE I Offices
ARTICLE II Stockholders
ARTICLE III Board of Directors
ARTICLE IV Committees
ARTICLE V Officers
ARTICLE VI Indemnification of Directors, Officers, Employees and Other Corporate Agents
ARTICLE VII Stock
ARTICLE VIII Miscellaneous
ARTICLE IX Amendment of Bylaws