Free Practice Questions for Nokia 4A0-112 Exam

Therouting table manager (RTM)is responsible for selecting the best route when multiple routing protocols provide a route for the same destination prefix. It makes the decision on which route to add to therouting tablebased on the administrative distance, metric, and other criteria.

The output shows two levels of IS-IS databases: Level 1 (L1) and Level 2 (L2). This indicates that the domain is multi-area, as L1 routers are confined to a single area, while L2 routers can route between different areas. The presence of Level 1/Level 2 (L1/L2) routers also suggests that the domain spans multiple areas.

The LSP (Link-State PDU) entries show L1/L2 ATT attributes, which typically indicate that these routers are capable of routing both within their own area (Level 1) and across areas (Level 2), suggesting a multi-area design.

The IS-IS domain likely includes broadcast interfaces, as indicated by the "ATT" attribute (typically referring to the type of interface) and common IS-IS configuration practices on broadcast networks like Ethernet.

When a router receives a CSNP (Complete Sequence Number PDU) that references an older LSP (Link-State PDU) than the one in its local database, it indicates that the neighbor is missing newer information.

In response, the router sends back a PSNP (Partial Sequence Number PDU) to the neighbor, which includes a copy of the LSPs it has in its local database that the neighbor may not yet have. This helps to synchronize the link-state information between routers.

Dividing a domain into areas typically does not reduce the number of routers needed to handle traffic. It is more focused on improving scalability, reducing the size of routing tables, and limiting the scope of SPF calculations, but it doesn't inherently reduce the number of routers required.

Router R1 is configured as L1/L2, meaning it is part of both Level 1 and Level 2 IS-IS routing areas. This means R1 will generate two types of LSPs:

Level 1 LSP (for the local area 49.0001) to advertise its local topology to other Level 1 routers.

Level 2 LSP (for the backbone area 49.0002) to advertise the global network topology to Level 2 routers.

R1 also has two broadcast interfaces, and as the Designated Intermediate System (DIS) on these interfaces, it will generate an LSP for each interface (one per broadcast link).

This results in three total LSPs:

A Level 1 LSP for the local area (49.0001).

A Level 2 LSP for the backbone area (49.0002).

An LSP for each of the two broadcast interfaces, which may include interface-related topology information.

While configuring areference bandwidth(which is used to calculate link costs) can be useful, it is not strictly required for IS-IS to run. IS-IS uses default bandwidth values to calculate costs, and it can function without explicitly configuring a reference bandwidth.

Based on theIPv6 route tableoutput forR3andR4, we can see that the routers have remote routes listed as"Remote ISIS", indicating that the route is being advertised from a different area (area 49.01 or 49.02). This is a sign ofroute leaking, where routes from one area are being shared across areas.

TheroutesfromR3(level-1 router) are being advertised toR4(level-1 router), and vice versa, withISISas the protocol. This implies that there is route leaking configured to allow information to pass between areas.

In IS-IS, routers are actually associated withinterfacesrather than the entire router being associated with a single area. A router can have interfaces in multiple areas, and it is the interface's configuration that determines which area it belongs to.

The Input/Output Module (IOM) is responsible for performing the longest prefix match (LPM) lookup on packets that arrive at the physical interfaces. The IOM performs this function by examining the destination IP address of incoming packets and using the routing table to determine the best match.