Exam JN0-351 topic 1 question 35 discussion

A and C are correct. A - correct. When an EBGP advertises a route to a different AS, it adds (appends) its own AS number to the AS_PATH. C - correct. If an EBGP router receives a route advertisement where its own AS number is already present in the AS_PATH, it rejects (drops) the route. This prevents routing loops because a route that has already passed through an AS should not be reintroduced into that same AS. D - Incorrect EBGP appends (adds) its AS number once to the AS_PATH, but prepending is an optional technique used for traffic engineering.

A and C are correct. Append is automatic and Doing Prepend is manual operation in BGP.

A and C are correct. Append is automatic and Doing Prepend is manual operation in BGP.

A. EBGP routers will append their AS number when advertising routes to their neighbors. - This is a fundamental mechanism of BGP. When an EBGP (External BGP) router advertises a route to a neighboring autonomous system, it appends (or prepends) its own AS number to the AS_PATH attribute. - This process provides a record of the ASes that the route has traversed, helping prevent routing loops by ensuring routers can detect if a route has already passed through their AS. C. EBGP routers will drop routes that contain their own AS number in the AS_PATH. - To prevent routing loops, an EBGP router will reject any routes that have its own AS number already present in the AS_PATH attribute. This ensures that the router does not reintroduce routes into its AS that have already traversed it.

Prepending: Used to manipulate path preference by making a route less attractive. It increases the AS path length, which can influence other ASes to prefer alternative, shorter paths.

CD. If 192.168.2.0/24 is advertised in the order 65001 65002 65003, the route will look like this: 192.168.2.0/24 65003 65002 65001 I Therefore the answer is D(prepend)

A C are correct.

C,D are correct

AC is correct https://networklessons.com/bgp/bgp-prevent-transit-as

Pls read again, its AC. Append means it adds the ASPath to the route and this is done just from ebgp. Prepend is used when we want to influence the routes.

CD is correct

When a BGP router advertises a prefix, it will include its own AS number to the left of the AS path attribute - aka prepending. Therefore C and D is correct