Question $10$: Consider the network shown below. Suppose AS$3$ and AS$2$ are running OSPF for their intra$-$AS routing protocol. Suppose AS$1$ and AS$4$ are running RIP for their intra$-$AS routing protocol. Suppose eBGP and iBGP are used for the inter$-$AS routing protocol. Initially suppose there is no physical link between AS$2$ and AS$4.$

$($a$)$ Router $3$c learns about prefix x from which routing protocol: OSPF, RIP, eBGP, or iBGP?

$($b$)$ Router $3$a learns about x from which routing protocol?

$($c$)$ Router $1$c learns about x from which routing protocol?

$($d$)$ Router $1$d learns about x from which routing protocol?

Question $11$: Consider the following network. ISP B provides national backbone service to regional

ISP A$.$ ISP C provides national backbone service to regional ISP D$.$ Each ISP consists of one AS$.$ B and C

peer with each other in two places using BGP$.$ Consider traffic going from A to D$.$ B would prefer to

hand that traffic over to C on the West Coast $($so that C would have to absorb the cost of carrying the

traffic cross$-$country$),$ while C would prefer to get the traffic via its East Coast peering point with B $($so

that B would have carried the traffic across the country$).$ What BGP mechanism might C use, so that

B would hand over A$-$to$-$D traffic at its East Coast peering point? To answer this question, you will

need to dig into the BGP specification.