url rewrite

Hello all,

 I have 4 pages calles page1.aspx, page2.aspx, page3.aspx and page4.aspx with totally different layouts.

I have 4 url rewrite rules like this

page1.aspx?a=xxx => page1.aspx/xxx

page2.aspx?b=yyy => page2.aspx/yyy

When a user enters www.test.com/xxx how can I swich between page1 and page2?

Kind Regards,

Bert
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