You are asked to implement route damping on a BGP router. There are two specific requirements for your
implementation:
1. damp all prefixes with a mask length equal to or greater than /24 more aggressively than routes with a mask
length between /17 and /23;
2. damp prefixes with a mask length between /0 and /16 less than routes with a mask length greater than /16.
Which policy configuration meets the requirement?

A.
[edit policy-options]
user@router# show
policy-statement damping {
term 1 {
from {
route-filter 0.0.0.0/0 prefix-length-range /0-/16 damping minor;
route-filter 0.0.0.0/0 prefix-length-range /24-/32 damping major;
}
then accept
}
}
damping major {
half-life 30;
suppress 2500;
}
damping minor {
half-life 5;
}

B.
[edit policy-options]
user@router# show
policy-statement damping {
term 1 {
from {
route-filter 0.0.0.0/0 prefix-length-range /0-/23 damping minor;
route-filter 0.0.0.0/0 prefix-length-range /24-/32 damping major;
}
then accept
}
}
damping major {
half-life 30;
suppress 2500;
}
damping minor {
half-life 5;
}

C.
[edit policy-options]
user@router# show
policy-statement damping {
term 1 {
from {
route-filter 0.0.0.0/0 prefix-length-range /0-/23 damping minor;
route-filter 0.0.0.0/0 prefix-length-range /24-/32 damping major;
}
then accept
}
}
damping major {
half-life 5;
}
damping minor {half-life 30;
suppress 2500;
}

D.
[edit policy-options]
user@router# show
policy-statement damping {
term 1 {
from {
route-filter 0.0.0.0/0 prefix-length-range /0-/16 damping minor;
route-filter 0.0.0.0/0 prefix-length-range /24-/32 damping major;
}
then accept
}
}
damping major {
half-life 5;
}
damping minor {
half-life 5;
suppress 2500;
}

Explanation:
The default half-life is 15 minutes.
The default value of suppress is 3000.
To aggressively damp prefixes we should increase half-life, to for example 30 minutes, and to decrease the
damp we should lower the half-life, to for example 5.
Incorrect Answers:
B, C: The intervals in the route filter should be /0-/16 and /24-/32, not /0-/23 and /24-/32.
D: We should increase half-life, not decrease it to 5.
http://www.juniper.net/documentation/en_US/junos16.1/topics/usage-guidelines/policy-usingrouting-policies-to-damp-bgp-route-flapping.html