Module 6

Question 1

Routers

Answer 1

can send traffic b/w locally connected networks by default. Reference their (IP routing tables) 2 route traffic

Question 2

CLI Command (Show IP Route)

Answer 2

!. Shows all known routes

2. Directly Connected routes.
3. Dynamically learned routes.
4. Static Routes.
5. Gateway of last resort aka default route.

Question 3

Static Route

Answer 3

Is a manually configured route in a router. Overrides dynamically learned routes by default. It is not fault tolerant so if the route drops or has a problem the router would not have a fall over (alternate route).

Question 4

Dynamic Route

Answer 4

the routing protocol that learns where 2 send routed protocols. Allows router 2 dynamically learn & share routes w/ 1 another aka (Autonomous System AS).

Question 5

Interior Gateway Protocols - IGP

Answer 5

share router information in a single (AS). Uses protocols RIP, IGRP, EIGRP, OSPF, IS-IS.

Question 6

Exterior Gateway Protocols - EGP

Answer 6

share routing information b/w AS. Uses protocol BGP & EGP=abosulute no longer in use.

Question 7

Link-State - LS

Answer 7

1/3 categories for routers to learn & share info. Uses the Dijkstra algorithm to find path w/ lowest cost/hops b/w node s(shortest path). Every node builds a graph of the network showing connected nodes & other nodes. Ex protocols OSPF & IS-IS

Question 8

Distance-Vector - DV

Answer 8

2/3 categories for routers. It calculates the distance & direction (vector) 2 a network. Uses algorithms as Bellman-Ford & DUAL (cisco proprietary). Ex. protocols RIP, IGRP, EIGRP, & BGP.

Question 9

Routing Information Protocol - (RIP)

Answer 9

is one of the oldest D-V routing protocols which employs the hop count as a routing metric. RIP prevents routing loops by implementing a limit on the number of hops allowed in a path from source to destination (15 hops) 16+ = infinity. RIPv1 no longer used. is classful. RIPv2 classless in use can route to all class & subnetted class.

Question 10

Interior Gateway Routing Protocol -(IGRP)

Answer 10

is a D-V IGP developed by Cisco. It is used by routers to exchange routing data within an AS. Created in part to overcome the limitations of RIP when used within large networks.No longer used.

Question 11

Enhanced Interior Gateway Routing Protocol - (EIGRP)

Answer 11

is an advanced D-V routing protocol that is used on a computer network for automating routing decisions and configuration. An IGP, uses DUAL, simple 2 configure & loop-free, rapid convergence, & has primary & secondary route respectively.

Question 12

Border Gateway Protocol - (BGP)

Answer 12

is a standardized EGP designed to exchange routing and reachability information between (AS) on the Internet. Classified as a path vector/ D-V routing protocol. eBGP (outside AS) & iBGP (inside AS), neighbors are called BGP peers.

Question 13

Open Shortest Path First - OSPF

Answer 13

is one of the families of IP Routing protocols, and an (IGP) for the Internet, used to distribute IP routing information throughout a single (AS) in an IP network. It is L-S, uses the Dykstra algorithm, has hierarchical “areas”, area 0 = backbone.

Question 14

Intermediate System 2 Intermediate System - IS-IS

Answer 14

is one of the families of IP Routing protocols, and is an (IGP) for the Internet, used to distribute IP routing information throughout a single (AS) in an IP network. It accomplishes this by determining the best route for data through a Packet switching network.

Question 15

Update Timer

Answer 15

30s timer to send RIP table update

Question 16

Invalid Timer

Answer 16

invalidates(removes) a router after no updates for 180s.

Question 17

Hold Down Timer

Answer 17

delays route installation by 180s after invalidation. Also prevents loop.

Question 18

Flush Timer

Answer 18

a route is removed after 240s from the last update route.

Question 19

Routing Loops

Answer 19

an invalid router that causes traffic 2 be sent back in the same direction it was received causing a loop (∞). Causes are slow routing protocols, old protocols (EGP), reverse route advertisement ( router send update list 2 each other), & static route ( if route point 2 each other).

Question 20

Split horizon - Loop Prevention

Answer 20

makes router not advertise back 2 the route it received updated routing table.

Question 21

Route Poisoning - Loop Prevention

Answer 21

advertise 2 networks that a route has infinite metric & it poison ( blocks) it.

Question 22

Poison Reverse - Loop Prevention

Answer 22

advertise 2 networks of a route poisoning by neighbors.

Question 23

Administrative Distance - AD

Answer 23

a #used 2 rank directly connected routes, Static routes, & dynamic routes from most desirable (0) to least desirable (255). If multiple routes exist in a specific destination lowest AD # will be chosen.

Question 24

Hop Redundancy

Answer 24

failover redundancy 4 network gateways aka a 2nd default gateway 4 a LAN). Supported on routers & L3 switches, only 1 router is the active gateway. Uses protocols HSRP, VRRP, GLBP, & CARP.

Question 25

Hot Standby Router Protocol - HSRP

Answer 25

is a Cisco proprietary redundancy protocol for establishing a fault-tolerant default gateway. Popular & easy 2 us.

Question 26

Virtual Router Redundancy Protocol - (VRRP)

Answer 26

is a computer networking protocol that provides for automatic assignment of available (IP) routers to participating hosts. This increases the availability and reliability of routing paths via automatic default gateway selections on an IP subnetwork. Functions similar to HSRP & open source.

Question 27

Gateway Load Balancing Protocol - (GLBP)

Answer 27

cisco owned. Presents multiple gateways in a single instance. Provides load balancing across gateways. Protects data traffic from a failed router or circuit while allowing packet load sharing between a group of redundant routers.

Question 28

Common Address Redundancy Protocol -CARP

Answer 28

is a computer networking protocol that allows multiple hosts on the same LAN 2 share a set of IP addresses. Its primary purpose is to provide failover redundancy, especially when used with firewalls and routers.

Question 29

Access Control Lists

Answer 29

+ L3 & L4 security. Protects networks from outside attackers. Control the traffic in our network & identifies whose allowed in or out based on a list. Used in router, switches, & firewalls.

Question 30

Rules for ACLs

Answer 30

1. Create ACL. 2. Apply ACL. 3. need at least 1 permit statement in the list. 4. Processed from top 2 bottom. 5. 1 ACL can be applied per protocol, per interface, per direction.

Question 31

Standard ACL

Answer 31

filter based on the source (where traffic comes from) best to apply list close 2 the (Destination). # ranges from 1-99.

Question 32

Extended ACL

Answer 32

filters based on the protocol, source, destination, & port best to apply close to the (source). # ranges from 100 - 199.

Question 33

Network Address Translation - NAT

Answer 33

in its simplest form is a 1-1 address mapping. Performed on routers & firewalls. Associates an internal private IP @ into a public internet IP @.

Question 34

Source NAT

Answer 34

changes the source @ of the packets passing through the router. As the host communicates 2 the internet source IP address is changed 2 public IP @. Ex. 192.168.100.50 to 74.189.45.33

Question 35

Destination NAT

Answer 35

changes destination @ of the packets passing through the router. As communication happens from the internet 2 IP @. Ex. 74.189.45.33 to 192.168.100.50.

Question 36

Static NAT

Answer 36

manually maps a private host IP @ directly to a public IP @. 1-1).

Question 37

Dynamic NAT

Answer 37

a 1-1 translation using address pools. Pool are created for both private IP @ & public IP @. Requires multiple public IP @.

Question 38

Port Address Translation - PAT

Answer 38

are randomly generated TCP port #s that are used 2 track & keep separate each NAT session. #1 used to translate a group of private IP @ into public IP @ routable on the internet. SOHO (small office/home office) does this by default.