If you're using @Html.ActionLink() you should try try these ones.
@Html.ActionLink("MyAction", "MyController", new { }, new { @Class="class-name"})
with Areas
@Html.ActionLink("MyAction", "MyController", new { }, new {@Area = "MyArea" @Class="class-name"})
Sendind data
@using (Ajax.BeginForm("MyAction", "MyController", new { }, new AjaxOptions { HttpMethod = "POST" }, new { @Area = "MyArea" }))
Sending data with no Area
@using (Ajax.BeginForm("MyAction", "MyController", new AjaxOptions { HttpMethod = "POST" }));
Besides that, you can check the url which @gardarvalur has posted.
I hope it helps you.