Statement (A) is false because a BGP router does not advertise all learned routes. It first runs a best-path selection algorithm to determine the single optimal route for each destination prefix. Only this optimal route is installed in the BGP routing table and subsequently advertised to its BGP peers.

Statement (D) is false because BGP advertises routes from multiple sources, not just from Interior Gateway Protocols (IGPs). BGP's primary function is to exchange reachability information between Autonomous Systems, which includes advertising routes learned from other BGP peers (both EBGP and IBGP) as well as routes imported from IGPs or static configurations.

B. This statement is true. It accurately describes the fundamental BGP behavior where only the selected optimal path for a prefix is advertised to other peers.

C. This statement is true. It describes the BGP split-horizon rule for IBGP, which prevents a router from advertising a route learned from one IBGP peer to another IBGP peer to avoid routing loops within an AS.

1. Huawei HCIP-Datacom-Core Technology V1.0 Training Material.

Reference for A and B: In the BGP section

under "BGP Route Advertisement Rules

" the material states

"A BGP speaker advertises only the optimal routes in its BGP routing table to its peers." This directly confirms that statement B is true and statement A is false.

Reference for C: The same section on "BGP Route Advertisement Rules" states

"A BGP speaker does not advertise routes learned from an IBGP peer to other IBGP peers." This confirms statement C is true.

Reference for D: The rule "A BGP speaker advertises routes learned from an EBGP peer to all its BGP peers (EBGP and IBGP)" demonstrates that routes learned from other BGP speakers are advertised

making the claim that only IGP routes are advertised (statement D) false.

2. Huawei VRP V800R012C10 Product Documentation

BGP Configuration Guide.

Reference for A

B

D: In the section "BGP Fundamentals > BGP Route Advertisement

" the documentation explains that BGP selects an optimal route from multiple routes to the same destination and advertises only the optimal route to its peers. It also details how routes learned from EBGP peers are sent to all other peers

contradicting both A and D.

Reference for C: The section "BGP Fundamentals > IBGP" explicitly describes the split-horizon mechanism: "To prevent routing loops between IBGP peers

a device does not advertise routes learned from an IBGP peer to other IBGP peers."