Switches and Routers Quiz 3

What is ARP used for?

MAPS an IP address to a MAC address.

What does “administratively down” mean?

The interface was manually disabled using the shutdown command.

What command brings an interface up?

no shutdown

Commands to check Layer 1, 2, and 3 interface status?

show interfaces; show ip interface

“Serial is down, line protocol is down” indicates what?

Layer 1 physical failure.

What is setup mode?

Initial configuration wizard when no startup-config exists.

What is POST?

Power-On Self-Test run during router boot.

What does CLI stand for?

Command Line Interface.

What is an autonomous system?

A group of networks under one administrative control.

Does the IP address change at each hop?

No, it stays the same end-to-end.

Does the MAC address change at each hop?

Yes, it is rewritten by each router.

Example of a distance vector routing protocol?

RIP.

Example of a link state routing protocol?

OSPF.

Example of an advanced distance vector routing protocol?

EIGRP.

What is a classless routing protocol?

A routing protocol that carries subnet mask information.

Examples of classless routing protocols?

OSPF, EIGRP, RIPv2.

What is administrative distance?

A value indicating route trustworthiness; lower is preferred.

Administrative distance of a static route?

1.

Administrative distance of OSPF?

110.

Administrative distance of EIGRP?

90.

Administrative distance of RIP?

120.

Advantage of static routing?

Secure and predictable.

Disadvantage of static routing?

No automatic failover.

Example of an IGP?

OSPF or EIGRP.

Example of an EGP?

BGP.

Purpose of OSPF hello timer?

Maintains and discovers neighbor relationships.

Purpose of OSPF dead timer?

Time before declaring a neighbor down.

What three things must a router know to route packets?

Destination network, next-hop address, exit interface.

Collision domains: Hub vs Switch?

Hub has one; switch has one per port.

What is a broadcast domain?

Area where all devices receive broadcast frames.

Three functions of a Layer 2 switch?

Address learning, forwarding/filtering, loop prevention.

Advantages of Layer 2 switching?

High performance and low latency.

What is a broadcast storm?

Excessive broadcasts overwhelming the network.

What prevents broadcast storms?

STP (Spanning Tree Protocol).

What is port security?

Restricting which MAC addresses can access a port.

What is an access port?

A port assigned to a single VLAN.

What is a trunk port?

A port that carries multiple VLANs.

What is frame tagging?

Marking frames with VLAN IDs on trunk links.

What trunking protocol is industry standard?

802.1Q.

What is router-on-a-stick?

Router subinterfaces routing between VLANs.

What is a VLAN?

A logical Layer 2 network segment.

What is a flat network?

One large broadcast domain without segmentation.

What is an ASIC?

Hardware chip enabling high-speed switching.

What is EtherChannel?

Combines multiple physical links into one logical link.

What is STP?

Spanning Tree Protocol; prevents switching loops.

What does STP select first?

A root bridge.

What is convergence?

Routers and switches agree on a consistent network topology.

What does ping do?

Tests connectivity using ICMP echo.

What does traceroute do?

Shows the path packets take to a destination.

Advantage of ping on a router vs a PC?

Tests routing using the router’s interfaces and routing table.

What is line protocol down usually caused by?

Layer 2 issues like encapsulation mismatch.

What is VLSM?

Variable Length Subnet Masking.

Which routing protocols support VLSM?

OSPF, EIGRP, RIPv2.

What is an LSA?

OSPF Link State Advertisement.

Why is OSPF hierarchical?

Uses areas to reduce overhead and improve scalability.

What metric does EIGRP use?

Bandwidth and delay.

What is dynamic routing?

Routes learned automatically via a routing protocol.

What is a default route?

0.0.0.0/0.

What is a hub-and-spoke topology?

Central router connects multiple remote sites.

What is line protocol?

Layer 2 status of an interface.

What is CDP?

Cisco Discovery Protocol; discovers directly connected neighbors.

Interior Gateway Protocol (IGP)

Routing protocols used inside an autonomous system

Exterior Gateway Protocol (EGP)

Used to route between autonomous systems

Distance Vector Routing Protocol

Determines the best path based on distance (hop count)

Link-State Routing Protocol

Builds a complete map of the network.

Advanced Distance Vector Protocol

Combines features of distance vector and link-state routing.

RIP (Routing Information Protocol)

A distance vector protocol using hop count as the metric. Maximum of 15 hops.

RIPv2

Improved version of RIP that supports VLSM and multicast updates

OSPF (Open Shortest Path First)

A link-state routing protocol that uses cost as its metric.

EIGRP (Enhanced Interior Gateway Routing Protocol)

An advanced distance vector protocol using bandwidth and delay as metrics.