EIGRP Filtering with Prefix-list

Hi guys,

CCIE R&S v5 Advanced Technology Labs - EIGRP, EIGRP Filtering with Prefix-list - Task 2 says to configure a prefix-list on R1 so that it does not install any updates received from R4 on the VLAN 146 segment.

The solution says to create two prefix-lists, one that will deny R4`s IP on the VLAN 146 segment, and one that will permit all prefixes.

 Config:

ip prefix-list NOT_FROM_R4 seq 5 deny 155.1.146.4/32
ip prefix-list NOT_FROM_R4 seq 10 permit 0.0.0.0/0 le 32
!
ip prefix-list PERMIT_ALL seq 5 permit 0.0.0.0/0 le 32
!
router eigrp 100
 distribute-list prefix PERMIT_ALL gateway NOT_FROM_R4 in

But, do we really need the PERMIT_ALL prefix-list?
Wouldn`t "distribute-list gateway NOT_FROM_R4 in" do the same trick?

My solution was to just use "distribute-list gateway R4 in Gi1.146", where R4 is a prefix-list denying 155.1.146.4/32 and permitting everything else (0.0.0.0/0 le 32).
After applying this the following commands only shows 155.1.146.6, indicating that the config was successful.

R1#sh ip eigrp top | i 155.1.146
        via 155.1.146.6 (3328/3072), GigabitEthernet1.146
        via 155.1.146.6 (131072/130816), GigabitEthernet1.146
P 155.1.146.0/24, 1 successors, FD is 2816
        via 155.1.146.6 (3328/3072), GigabitEthernet1.146
        via 155.1.146.6 (3072/2816), GigabitEthernet1.146
        via 155.1.146.6 (3584/3328), GigabitEthernet1.146
        via 155.1.146.6 (130816/128256), GigabitEthernet1.146
        via 155.1.146.6 (131328/131072), GigabitEthernet1.146

R1#sh ip route eigrp | i 155.1.146
D        150.1.6.6 [90/130816] via 155.1.146.6, 00:01:13, GigabitEthernet1.146
D        150.1.7.7 [90/131072] via 155.1.146.6, 00:01:13, GigabitEthernet1.146
D        150.1.9.9 [90/131328] via 155.1.146.6, 00:01:13, GigabitEthernet1.146
           [90/3328] via 155.1.146.6, 00:01:13, GigabitEthernet1.146
           [90/3584] via 155.1.146.6, 00:01:13, GigabitEthernet1.146
           [90/3072] via 155.1.146.6, 00:01:13, GigabitEthernet1.146
           [90/3328] via 155.1.146.6, 00:01:13, GigabitEthernet1.146

R1#sh ip eigrp top 150.1.4.4/32

EIGRP-IPv4 Topology Entry for AS(100)/ID(150.1.1.1) for 150.1.4.4/32
 State is Passive, Query origin flag is 1, 1 Successor(s), FD is 27008256
 Descriptor Blocks:
 155.1.0.5 (Tunnel0), from 155.1.0.5, Send flag is 0x0
     Composite metric is (27008256/130816), route is Internal
     Vector metric:
       Minimum bandwidth is 100 Kbit
       Total delay is 55010 microseconds
       Reliability is 255/255
       Load is 1/255
       Minimum MTU is 1400
       Hop count is 2
       Originating router is 150.1.4.4
 155.1.13.3 (GigabitEthernet1.13), from 155.1.13.3, Send flag is 0x0
     Composite metric is (27008512/27008256), route is Internal
     Vector metric:
       Minimum bandwidth is 100 Kbit
       Total delay is 55020 microseconds
       Reliability is 255/255
      Load is 1/255
     Minimum MTU is 1400
      Hop count is 3
      Originating router is 150.1.4.4

Would this approach have any affect on the grading on the lab?