Full permission but why can’t access the file in group mode| group permission vs home user root directory permission

Consider the student group has the two member user1 and user2 .User1 has the file file1 and user1 give the full permission for file1 777 to access the group member. but the same group member user2 can not access the file1(But

you thing user2 can access file1).because user2 have the permission to access the file only for file1.but user2 does not have any permission to access dir /home/user1.Then how is it possible user2 access the file1.If user2 have the permission to access the dir
/home/user1 then only he can access the file /home/user1/file1.
you can try it
now.
Testing for the problem.

step1: create the group student and add the user1 and user2 to the group student
[root@localhost ~]# groupadd student
adduser1,2 to group student then
[root@localhost ~]# usermod -G student user1
[root@localhost ~]# usermod -G student user2

step2:now login to the user1
Create the file file1.Then give the full permission

[user1@localhost ~]$ touch file1
[user1@localhost ~]$ chmod 777 file1
[user1@localhost ~]$ ls -l
total 8
-rwxrwxrwx 1 user1 user1 1 Apr 11 00:26 file1



step3:Login to the user2
Access the user1.file1
[user2@localhost ~]$ cat /home/user1/file1
cat: /home/user1/file1: Permission denied

step4: Do you know why user2 can not access user1/file1 with full permission.
Because user2 have the permission only for the file1.but he does not have the permission to access the dir /home/user1


step5:so change the /home/user1 permission to 717
[user1@localhost ~]$ chmod 717 /home/user1
Now user2 can access the user1.file1 file because user2 have the permission to execute folder /home/user1