M6Q25: Routing Flashcards
When a Router receives an IP Packet it checks the destination IP address and then references it’s ________________ before making a decision on where to send the Packet.
A. Gateway
B. Routing Table
C. ARP Cache
D. Interface
B. Routing Table
Explanation: Routers always reference their routing table to make decisions on where to route packets. The routing table includes all know routes from connected interfaces, dynamically learn routes from routing protocols and static routes.
This type of route is always entered into a router manually and does not change unless an administrator updates the route.
A. Dynamic route
B. Gateway of last resort
C. Static route
D. Default route
C. Static
Explanation:Static routes are routes that are configured manually and are always present in the router unless removed or changed by an administrator. A dynamic route is learned from other routers and the route itself is not entered manually. A default route can be entered statically, but can also be learned dynamically. The Gateway of last resort is the same thing as a default route.
Dynamic routing is when routers share routes with each other via routing protocols.
A. True
B. False
A. True
Explanation:Routers running the same routing protocol are able to share routes with each other and dynamically learn about changes to the routing topology. This is called dynamic routing.
An Exterior Gateway routing protocol shares routes within a single autonomous system.
A. True
B. False
B. False
Explanation:Exterior Gateway routing protocols share routes between different autonomous systems, whereas Interior Gateway routing protocols share routes within a single autonomous system.
Select the Interior Gateway routing protocols from the list below.
(select all that apply)
A. BGP
B. RIP
C. IS-IS
D. EIGRP
E. OSPF
F. IGRP
G. EGP
B (RIP), D (EIGRP), E (OSPF), F (IGRP)
Explanation: RIP, IGRP, EIGRP, and OSPF are all Interior Gateway routing protocols whereas EGP, BGP, and IS-IS are Exterior Gateway routing protocols.
Which of the following routing protocols are link-state routing protocols.
(select all that apply)
A. BGP
B. RIP
C. IS-IS
D. EIGRP
E. OSPF
F. IGRP
G. EGP
C (IS-IS), E (OSPF)
Explanation: OSPF and IS-IS are based on link-state algorithms and are link-state routing protocols.
EIGRP is referred to as a Hybrid routing protocol.
A. True
B. False
A. True
Explanation:Sometimes called an Advanced Distance Vector routing protocol, EIGRP is also referred to as a Hybrid routing protocol and uses the Diffusing Update Algorithm (DUAL).
The default metrics for EIGRP are:
(select two)
A. Bandwidth
B. Path Cost
C. Latency
D. Delay
A (Bandwidth), D (Delay)
Explanation: Although more metrics can be configured by an administrator, Bandwidth and Delay are the Default metrics for EIGRP.
This interior gateway routing protocol uses hierarchical “areas” with Area 0 being the “backbone area”. Although all routers can be placed within the backbone area, the autonomous system can also be divided up into multiple areas to keep the routing databases at manageable sizes and reduce the overall amount of routing updates in larger autonomous systems.
A. EIGRP
B. BGP
C. OSPF
D. IS-IS
C. OSPF
Explanation: OSPF (Open Shortest Path First) is an interior gateway routing protocol and the only routing protocol that uses areas to segment the autonomous system into multiple routing domains.
This routing protocol is considered to be the “Routing Protocol of the Internet” and can be used to participate in public internet routing, learning and sharing routes with other autonomous systems.
A. EIGRP
B. BGP
C. OSPF
D. RIPv2
B. BGP
Explanation: BGP (Border Gateway Protocol) is an exterior gateway routing protocol and can be used on the edge of an autonomous system to dynamically share routes with other autonomous systems. BGP uses a distance-vector/path-vector based algorithm and is considered to be the primary routing protocol of the internet.
This routing protocol is a classfull routing protocol meaning it does not support VLSM or common subnetting.
A. RIPv1
B. EIGRP
C. OSPF
D. RIPv2
A. RIPv1
Explanation: RIPv1 (Router Information Protocol version 1) is classfull meaning it does not support subnetting. RIPv2 should always be used instead of RIPv1 as RIPv2 supports subnetting and is a modern classless routing protocol.
This routing protocol is a purely distance vector routing protocol and uses hop count as its only metric with 15 hops being the maximum.
A. BGP
B. EIGRP
C. OSPF
D. RIPv2
D. RIPv2
Explanation: Both versions of RIP (RIPv1 and RIPv2) are based on a purely distance vector algorithm and have a 15 hop count limitation.
When routing protocol updates occur and all the routers in the autonomous system have been updated it is called _______________.
A. Learning
B. Summarization
C. Convergence
D. Agreement
C. Convergence
Explanation: When all routers have received routing protocol updates and agree on the same routing topology it can be said that the routers and their routing tables have “converged”.
Users at headquarters are complaining that they can’t access network resources at one of the branch offices. You perform a ping to the branch office and you get no replies. Then, you perform a traceroute to the branch office and you see the traceroute continues to bounce back and forth between two router IP addresses continuously. What is this a sign of?
A. A good configuration
B. Routing Protocols
C. Split Horizon
D. A Routing Loop
D. A Routing Loop
Explanation: When a routing loop occurs it will take the network offline that is involved in the loop. In this case a branch office was taken offline by a routing loop which was confirmed by the traceroute output that should the trace bounding back and forth between two different routers. This is exactly what a routing loop is – two routers that keep sending packets for a specific destination back to each other because they each think the other router knows how to get to the destination. Normally this type of routing problem is caused by a bad static route that an administrator entered in by mistake or without knowing it would create a loop. Modern Routing protocols are said to be loop free and routing protocols can help to prevent scenarios like this when there are multiple locations and networks all interconnected with routers. However, it should be understood that a static route will always override a routing protocol and therefore an administrator can still break a network by entering an invalid static route even if routing protocols are being used.
When a router advertises a failed route as an infinite metric for routing loop prevention it is called _____________.
A. Route Poisoning
B. Split Horizon
C. Maximum Hop Count
D. A Hold Down Timer
A. Route Poisoning
Explanation: Routers employ many methods to prevent loops. Route Poisoning is one of many methods and entails advertising failed routes with an infinite metric so that other routers will know that it is a bad route.
