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Exam JN0-648 topic 1 question 13 discussion

Actual exam question from Juniper's JN0-648
Question #: 13
Topic #: 1
[All JN0-648 Questions]

Click the Exhibit button.

The policy shown in the exhibit is applied as an export policy to your BGP neighborship.
Which action will be taken for route 12.233.45.5?

  • A. It will rejected by term 2.
  • B. It will be accepted by term 1.
  • C. It will be accepted by the default policy.
  • D. It will be evaluated by the next policy.
Show Suggested Answer Hide Answer
Suggested Answer: B 🗳️

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Essentialroot
Highly Voted 3 years, 2 months ago
Seems like the correct answer is D. All the prefix-lists are used in the policy terms without specified keyword *orlonger*. It means that (the juniper docs says): "As you can see, the prefix list does not contain a match type for each route (as you would see with a route filter). This is an important point when using a prefix list in a policy. Routes match only if they exactly match one of the prefixes in the list. In other words, each route in the list must appear in the routing table exactly as it is configured in the prefix list.". That means if the is question asked about the 12.233.45.5/32 as the consequence term 1 and term 2 wouldn't be triggered at all.
upvoted 17 times
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SB13
Highly Voted 3 years, 5 months ago
Which action will be taken for route 12.233.45.5? This is part of the "known-ok-sites" subnet of 12.233.0.0/18. So it will be allowed by term 1. B is correct
upvoted 14 times
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Gruizzy
Most Recent 2 years, 1 month ago
Selected Answer: D
D is the good answer. Please update
upvoted 1 times
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Hallie026
2 years, 2 months ago
Correct answer Should be D. Prefix-list is nog matched because it”s missing le or ge statement
upvoted 1 times
wassupkay
1 year, 9 months ago
this is a prefix-list it doesn't use le or get
upvoted 1 times
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nushadu
2 years, 4 months ago
ed@vMX-PE1# show policy-options | display set set policy-options prefix-list PL_33 3.3.3.0/24 set policy-options policy-statement EBGP-TO-IBGP term 70 from prefix-list PL_33 set policy-options policy-statement EBGP-TO-IBGP term 70 then next-hop self set policy-options policy-statement EBGP-TO-IBGP term 70 then accept set policy-options policy-statement EBGP-TO-IBGP term 80 from protocol bgp set policy-options policy-statement EBGP-TO-IBGP term 80 from route-filter 3.3.3.33/32 exact set policy-options policy-statement EBGP-TO-IBGP term 80 to protocol bgp set policy-options policy-statement EBGP-TO-IBGP term 80 then reject set policy-options policy-statement EBGP-TO-IBGP term 90 from protocol direct set policy-options policy-statement EBGP-TO-IBGP term 90 from route-filter 10.0.13.0/24 exact set policy-options policy-statement EBGP-TO-IBGP term 90 then accept set policy-options policy-statement EBGP-TO-IBGP term 100 from protocol bgp set policy-options policy-statement EBGP-TO-IBGP term 100 then next-hop self set policy-options policy-statement EBGP-TO-IBGP term 100 then accept set policy-options policy-statement EBGP-TO-IBGP then reject
upvoted 1 times
nushadu
2 years, 4 months ago
ed@vMX-PE1# show protocols bgp group iBGP | display set set protocols bgp group iBGP type internal set protocols bgp group iBGP local-preference 125 set protocols bgp group iBGP local-address 1.1.1.1 set protocols bgp group iBGP import IMPORT-TO-iBGP set protocols bgp group iBGP family inet unicast set protocols bgp group iBGP export EBGP-TO-IBGP set protocols bgp group iBGP neighbor 2.2.2.2
upvoted 1 times
nushadu
2 years, 4 months ago
ed@vMX-PE1# run show route advertising-protocol bgp 2.2.2.2 inet.0: 18 destinations, 21 routes (18 active, 0 holddown, 0 hidden) Prefix Nexthop MED Lclpref AS path * 3.3.3.3/32 Self 0 125 3 I * 10.0.13.0/24 Self 125 I [edit] ed@vMX-PE1#
upvoted 1 times
nushadu
2 years, 4 months ago
ed@vMX-PE1# show | compare [edit policy-options policy-statement EBGP-TO-IBGP term 70 from] - prefix-list PL_33; [edit policy-options policy-statement EBGP-TO-IBGP term 70 from] + prefix-list-filter PL_33 orlonger; [edit] ed@vMX-PE1# commit check configuration check succeeds [edit] ed@vMX-PE1# commit commit complete [edit] ed@vMX-PE1# run show route advertising-protocol bgp 2.2.2.2 inet.0: 18 destinations, 21 routes (18 active, 0 holddown, 0 hidden) Prefix Nexthop MED Lclpref AS path * 3.3.3.3/32 Self 0 125 3 I * 3.3.3.33/32 Self 0 125 3 I * 10.0.13.0/24 Self 125 I [edit] ed@vMX-PE1#
upvoted 1 times
nushadu
2 years, 4 months ago
Guys, "prefix-list" will match EXACT prefix (in this case /18) so it will not match address 12.233.45.5/32 if you want to match this address 2.233.45.5/32 with prefix-list you should use "prefix-list-filter" (it will allow you to use the statement "orlonger") I tested this behaviour in the lab (please see my output above) So correct answ. is D. D. It will be evaluated by the next policy. because it will not be matched by terms 1 & 2 and matched by term 3
upvoted 1 times
nushadu
2 years, 4 months ago
keep in mind I my lab I played with addr 3.3.3.33/32 (instead of 12.233.45.5/32)
upvoted 1 times
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Merlin5326
3 years, 2 months ago
It will depend on how the route is in the routing table. If the route is 12.233.45.5/32, then term 3 will match, so D is the right answer, but if the route. The question is a little fague as to how the route looks, but based on how the question is posed, I would have to assume the route is indeed 12.233.45.5/32. According to this Juniper doc (https://www.juniper.net/documentation/en_US/junos/topics/example/policy-prefix-list.html), my understanding is the match-type still has to be specified in the policy statement term after the prefix list. Example: term 1 { from { prefix-list known-ok-sites orlonger; } the accept ..... which means term 1 and term 2 will only match exact prefix and mask
upvoted 6 times
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rrahim
3 years, 3 months ago
yep, B https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/policy-statement-edit-policy-options.html Generally, a router compares a route against the match conditions of each term in a routing policy, starting with the first and moving through the terms in the order in which they are defined, until a match is made and an explicitly configured or default action of accept or reject is taken. If none of the terms in the policy match the route, the router compares the route against the next policy, and so on, until either an action is taken or the default policy is evaluated. 12.233.0.0/18 = 12.233.0.1 - 12.233.63.254
upvoted 4 times
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TBT_1
3 years, 4 months ago
B is correct, as 10.233.45.5 lies within the subnet 10.233.0.0/18 that has a range of 10.233.0.1-10.233.63.254
upvoted 7 times
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Mooshy
3 years, 5 months ago
The Term 1 will have host range "10.233.0.1 - 10.233.63.254" so it will not be accepted . I think the address will be rejected by term 2.
upvoted 1 times
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