I just finished reading the first chapter of Practical BGP ISBN 0321127005 and here are my answers of the questions at the end of the chapter:

Question №1:
What is a routing domain from BGP’s perspective? How is this different from a routing domain within IS-IS?

Answer:
A routing domain from BGP’s perspective is the set of routes under the same administrative control, usualy referred as an Autonomus System. The difference is that in IS-IS a routing domain is the area in which topology information is spread.
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Question №2:
What are the two primary differences between an interior gateway protocol and an exterior gateway protocol?

Answer:
The Interior gateway protocol is used within an AS. Exterior gateway protocol is used for routing between AS. Also IGP don’t cary policy information.
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Question №3:
What types of policies would you normally see implemented through BGP?

Answer:
Two possible policies are to mark routes so they cannot be advertised beyond the adjacent routing domain and to prevent leakking of information that would provide a better route to internal networks that internal routing information provides. Also policy to take the closest exit point, one to take the cheapest exit point, one that should not allow traversing of certain networks.
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Question №4:
For what does BGP use the path information it carries through the network?

Answer:
To determine loop-free paths between AS.
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Question №5:
Why does BGP threat each autonomus system as a point on the connectivity graph?

Answer:
The main reason is to hide topological details of the AS.
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Question №6:
What transport does BGP use to build a session to another BGP speaker? What local port number and remote port number does BGP use when initiating a connection?

Answer:
It uses TCP for sessions between speakers. The local port number is a random number above 1024 and the remote port number is 179.
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Question №7:
How is a collision resolved between two BGP speakers attempting to open a connection at the same time?

Answer:
Whe a collision occurs (two routers try to initiate a session) only the session by the router with the largest router ID value is preserved. The other one is dropped.
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Question №8:
Define prefix, NLRI, and attribute.

Answer:
A prefix is a network address. NLRI stands for Network Layer Reachability Information and consists of set of destinations. An attribute is an array of informatino that holds various pieces of informationt such as path preference and others.
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Question №9:
How many sets of attributes can a single BGP update contain? How many prefixes?

Answer:
One set of attributes with many prefixes, to which the attributes apply.
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Question №10:
What are the four primary difference between eBGP peering relationships and iBGP peering relationships?

Answer:
* Routes learned from an iBGP peer are not advertised to other iBGP peers. (Prevents routing loops within the AS)
* The attributes of paths learned from iBGP peers are not changed to impact the path selection to reach some outside network.
* The AS Path is not manipulated when advertising a route to an iBGP peer; the local AS is added to the AS Path only when advertising a route to an eBGP peer.
* The BGP next hop is normally not changed when advertising a route to an iBGP; it is always changed to the local peer termination IP address when a route is being advertised to an eBGP peer.