<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
<ContentTemplate>
<%= DateTime.Now %>
<asp:Button ID="Button1" runat="server" Text="Button" />
</ContentTemplate>
<Triggers>
<asp:PostBackTrigger ControlID="Button2" />
</Triggers>
</asp:UpdatePanel>
<asp:UpdatePanel ID="UpdatePanel2" runat="server">
<ContentTemplate>
<%= DateTime.Now %>
<asp:Button ID="Button2" runat="server" Text="Button" />
</ContentTemplate>
</asp:UpdatePanel>
In this code, Button1 will update both UpdatePanels, Button2 will update both UpdatePanels, but Button2 will trigger a synchronous postback (whole page refresh).
