Refer to the exhibit.
You want to set up an AS path filter that allows networks that originated from AS4, and
autonomous systems that are directly attached to AS4, to enter R1. When you tested the filter, you
noticed that something was wrong with it.
How can this be solved?
A.
Change the regular expressing to ^4_0-9*$.
B.
Change the regular expression to ^4_0-9+$.
C.
Change the regular expression to ^4_0-9.*.
D.
Change the regular expression to ^4_0-9.$.