Juniper Updated JN0-351 Exam Questions and Answers by ian

An ISO NET address is a type of network address used by the IS-IS routing protocol.  It identifies a point of connection to the network, such as a router interface, and is also called a Network Service Access Point (NSAP) 1 .

An ISO NET address consists of three parts: an area ID, a system ID, and a selector 2 . The area ID identifies the IS-IS area to which the device belongs. The system ID uniquely identifies the device within the area.  The selector identifies a specific service or function on the device, such as routing or management 2 .

An ISO NET address must be unique for each device in the network, because it is used by IS-IS to establish adjacencies, exchange routing information, and compute shortest paths 2 . If two devices have the same ISO NET address, they will not be able to communicate with each other or with other devices in the network. Therefore, it is important to assign different ISO NET addresses to each device in the network.

A. The routes displayed have traversed one or more autonomous systems. True. The AS path attribute shows AS numbers (e.g., 65401 65520.), indicating the route ' s traversal through various autonomous systems. D. The routes displayed are being learned from an IBGP peer. True. The absence of the ' * > i ' marker before the prefixes indicates they are being learned from an IBGP peer. Therefore, the correct statements are A. The routes displayed have traversed one or more autonomous systems. and D. The routes displayed are being learned from an IBGP peer.

The maximum allowable MTU size for a default GRE tunnel without IPv4 traffic fragmentation is 1476 bytes 1 .  This is because GRE packets are formed by the addition of the original packets and the required GRE headers 1 .  These headers are 24-bytes in length and since these headers are added to the original frame, depending on the original size of the packet we may run into IP MTU problems 1 .  The most common IP MTU is 1500-bytes in length (Ethernet) 1 .  When the tunnel is created, it deducts the 24-bytes it needs to encapsulate the passenger protocols and that is the IP MTU it will use 1 .  For example, if we are forming a tunnel over FastEthernet (IP MTU 1500) the IOS calculates the IP MTU on the tunnel as: 1500-bytes from Ethernet - 24-bytes for the GRE encapsulation = 1476-Bytes 1 .

In BGP, the path selection process is based on a set of attributes 1 .  The process starts by preferring the path with the highest weight, then the highest local preference, then the locally originated routes, and so on 1 .  If all these attributes are the same, then it prefers the path with the shortest AS path 1 .

Referring to the exhibit, all four ISPs have the same weight, local preference, and origin 1 .  However, ISP 4 has the shortest AS path 1 . Therefore, ISP 4 will be selected as the active path. So, option C is correct.