Lets make a list of tags which actually take path to files or URL patters in web.xml (and which are covered in the exam, if I missed any you can add them)
url-pattern (inside
servlet-mapping,
filter-mapping and
web-resource-collection tags)
jsp-file (inside
servlet tag)
welcome-file (inside
welcome-file-list tag)
location (inside
error-page tag)
tag-lib-location (inside
taglib which is itself inside
jsp-config tag)
form-login-page and
form-error-page (inside
form-login-config tag)
Now see which tags can accept paths starting from / or without / or both and see if you can find any fix
pattern. Some of the information on the pages that I linked might be wrong, for example the value of
jsp-file tag must start with / as the spec says
Servlet 2.4 spec wrote:The jsp-file element contains the full path to a JSP file within the web application beginning with a “/”.