UpdatePanel和AutoCompleteExtender

<table  width="90%" bgcolor="white" class="tableBorder" cellpadding="0" cellspacing="0">
                <tr>
                    <td rowspan="4" style="text-align: center;">
        <asp:UpdatePanel ID="UpdatePanel2" runat="server">
            <ContentTemplate>
                <table style="width:400px">
                    <tr>
                        <td style="text-align: right; height: 24px; width: 197px;">
                            公司名称:</td>
                        <td>
                            <asp:DropDownList ID="Ddl_searchDepart" runat="server" AutoPostBack="True" OnSelectedIndexChanged="Ddl_searchDepart_SelectedIndexChanged"
                                Width="95px" CssClass="buttoncss">
                            </asp:DropDownList></td>
                        <td style="width: 152px; text-align: right; height: 24px;">
                            部门名称：</td>
                        <td style="width: 100px; height: 24px;">
                            <asp:DropDownList ID="Ddl_searchSr" runat="server" AppendDataBoundItems="True" Width="95px" CssClass="buttoncss">
                            </asp:DropDownList></td>
                        <td style="width: 101px; text-align: center; height: 24px;">
                            <asp:LinkButton ID="Lkb_search" runat="server" OnClick="Lkb_search_Click">查询</asp:LinkButton></td>
                    </tr>
                </table>
                &nbsp;
            </ContentTemplate>
        </asp:UpdatePanel>
         
       
        <table>
            <tr>
                <td style=" text-align: right;">
        姓名：</td>
                <td>
                    <asp:TextBox ID="Txt_Name" runat="server" CssClass="register_input"></asp:TextBox></td>
                <td style="text-align: center;">
                    <asp:LinkButton ID="lkb_SearchName" runat="server" OnClick="lkb_SearchName_Click">查询</asp:LinkButton></td>
            </tr>
        </table>问题：“AutoCompleteExtender”用于这里的“TextBox控件”，但是这个“TextBox控件”并没有被放在“UpdatePanel”控件的里面，这是不是说明，“AutoCompleteExtender控件”的使用和“UpdatePanel控件”没有关系？？？那么“UpdatePanel控件”有什么作用呢？异步刷新，不是只要设定自动回传不就OK了吗？？？

        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
            <ContentTemplate>
        <asp:GridView ID="GridView1"  runat="server"  CssClass="GridView" AutoGenerateColumns="False"   AllowPaging="True" OnPageIndexChanging="GridView1_PageIndexChanging" CellPadding="4" ForeColor="#333333" GridLines="None" >
        <Columns>
        <asp:TemplateField HeaderText="职工编号">
        <ItemTemplate>
         <%#Eval("ZGBH")%>
        </ItemTemplate>
        </asp:TemplateField>
                <asp:TemplateField HeaderText="姓名">
                        <ItemTemplate>
        <%#Eval("XM")%>
        </ItemTemplate>
        </asp:TemplateField>
                <asp:TemplateField HeaderText="身份证">
                        <ItemTemplate>
        <%# Eval("SFZ")%>
        </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="性别">
                        <ItemTemplate>
                        <%#Eval("XB")%>
        </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="出生日期">
                        <ItemTemplate>
                        <%# Eval("CSRQ")%>
        </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="入职日期">
                        <ItemTemplate>
                        <%# Eval("RZRQ")%>
        </ItemTemplate>
        </asp:TemplateField>
        <asp:TemplateField HeaderText="职务">
                        <ItemTemplate>
                        <%# Eval("ZW")%>
        </ItemTemplate>
        </asp:TemplateField>
               
        
                <asp:TemplateField HeaderText="详细信息">
                <ItemTemplate>
                <a href='<%# "detailed.aspx?key="+Eval("ZGBH") %>'>详细信息</a>
                </ItemTemplate>
        </asp:TemplateField>
        </Columns>
         <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" Height="25px"/>
         <RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
        <EditRowStyle BackColor="#999999" />
         <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
         <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
         <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White"  Height="25px"/>
         <AlternatingRowStyle BackColor="White" ForeColor="#284775" />
            <PagerSettings FirstPageText="第一页" LastPageText="最后一页" NextPageText="下一页" PreviousPageText="上一页" />
        </asp:GridView>
            </ContentTemplate>
        </asp:UpdatePanel>
        <cc1:AutoCompleteExtender ID="AutoCompleteExtender1" runat="server" CompletionInterval="100" MinimumPrefixLength="1" ServiceMethod="GetName" ServicePath="~/WebService/TxtName.asmx" TargetControlID="Txt_Name">
</cc1:AutoCompleteExtender>
                    </td>
                </tr>
                </table>