IS-IS Route Leaking

In order for R6 to reach R4 loopback network, it goes via R2 which is a longer path even though the nearest exit is R1 due to the lack of specific prefix.

R6#traceroute 4.4.4.4
Type escape sequence to abort.
Tracing the route to 4.4.4.4
  1 192.168.26.2 52 msec 40 msec 20 msec
  2 192.168.23.3 44 msec 28 msec 44 msec
  3 192.168.13.1 72 msec 56 msec 56 msec
  4 192.168.14.4 64 msec *  56 msec

R1 Configuration

access-list 100 permit ip host 4.4.4.4 host 255.255.255.255
!
router isis
 redistribute isis ip level-2 into level-1 distribute-list 100

Verification

R6#traceroute 4.4.4.4
Type escape sequence to abort.
Tracing the route to 4.4.4.4
  1 192.168.56.5 52 msec 32 msec 8 msec
  2 192.168.15.1 52 msec 40 msec 52 msec
  3 192.168.14.4 76 msec *  60 msec

GNS File : http://www.4shared.com/rar/-KuB3a1B/isis_route_leaking.html