This configuration applies to IGMP (Internet Group Management Protocol) and is designed to control multicast group memberships on the interface ge-0/0/0.0.
Breaking Down the Configuration Policy-Statement: block-igmp
policy-statement block-igmp {
term 1 {
from {
route-filter 224.7.7.7/32 exact;
source-address-filter 192.168.100.10/32 exact;
}
then reject;
}
}
This policy blocks IGMP joins for group 224.7.7.7 only if the source IP is 192.168.100.10.
If both conditions match, the request is rejected.
IGMP Configuration on Interface ge-0/0/0.0
[edit protocols igmp]
user@router# show
interface ge-0/0/0.0 {
group-policy block-igmp;
group-limit 25;
}
group-policy block-igmp applies the policy statement block-igmp, meaning IGMP join requests are evaluated based on this policy.
group-limit 25 means the interface allows up to 25 multicast groups.
Evaluating the Answer Choices
✅ A. Joins for group 224.7.7.7 are rejected if the source address is 192.168.100.10.
Correct, because:
The policy specifically matches group 224.7.7.7 and source IP 192.168.100.10.
If both conditions are met, the join is rejected.
❌ B. Joins for any group are accepted if the group count value is less than 25.
Incorrect, because:
The group-limit (25) applies to the total number of IGMP groups but does not override explicit policy rules.
Even if there are fewer than 25 groups, a join request can still be rejected by the policy statement.
❌ C. Joins for group 224.7.7.7 are always rejected, regardless of the group count.
Incorrect, because:
The policy only blocks joins from the specific source 192.168.100.10.
Joins from other sources to 224.7.7.7 are allowed.
❌ D. Joins for group 224.7.7.7 are accepted if the group count is less than 25.
Incorrect, because:
Joins for 224.7.7.7 from source 192.168.100.10 will always be rejected, even if the group count is below 25.
The group-limit does not override the rejection policy.
"Joins for group 224.7.7.7 are rejected if the source address is 192.168.100.10." Official Juniper Documentation Reference:
Junos IGMP Policy Configuration Guide
"A group-policy statement allows filtering IGMP joins based on multicast group address and source IP."