| Question | Answer |
| key functions of a router | switching from interfaces
acting as intersection between multiple networks
forwards packets to destination network |
| what do these components of routers do?
NVRAM
RAM(SD RAM)
Flash
ROM | NVRAM: where startup config is stored
RAM(SD RAM): where routing tables and mac addresses are stored (goes away when turned off)
Flash: where IOS is stored
ROM: a limited, stripped down IOS for emergencies |
| four steps to router bootup
(in order) | 1. power on self test (POST)
2. bootstrap check
3. loads IOS from flash
4. startup configuration from NVRAM |
| how do you identify a:
Level 1 route
ultimate route
parent
child | ultimate: has out going interface or next hop IP
level 1: classful or supernetted, ultimate
child: always an ultimate route, and supernetted
parent: no outgoing interface, always classful or supernetted |
| how do you select the routing protocol if there are more than one that lead to the same destination network? | Pick the protocol with the lowest administrative distance (EIGRP) |
| What are the characteristics of a link-state routing protocol | 1. updates are sent to everybody in a network
2. sends updates periodically/only when needed
3. complete topological view of network
4. uses dijkstra shortest route first |
| what information can be learned from the show ip route command? | 1. which routing protocols used (can tell by administrative distance)
2. networks
3. metrics |
| what is the purpose of a metric in a routing protocol? | to compare and determine the best route |
| what are the default metrics for these routing protocols:
RIP
EIGRP
OSPF | RIP: hop count
EIGRP: bandwidth & delay
OSPF: cost (inverse of bandwidth) |
| what do these metric values measure?
hop count
cost
bandwidth | hop count: how many routers are between you and the destination network
cost: the value to indicate preference for a route
bandwidth: speed of a link |
| what do these metric values measure?
delay
load
reliability | delay: the time difference of what it takes and what it should take
load: the amount of data/traffic on a link
reliability: the amount of errors on a link |
| which routing protocols support VLSM and therefore discontiguous networks? | OSPF
EIGRP
ISIS
RIPv2 |
| which two devices can be used to connect to the internet? | modem (for DCE devices)
CSUDSU (digital modems) |
| When should these cables be used?
patch (straight-through)
crossover
rollover | patch (straight-through): unlike devicecs
crossover: like devices
*except computer--router or switch--hub
rollover: console port on route--serial port on computer |
| which port should be used to configure a new router or one that has been erased? | console port |
| how do you access these router prompt modes?
user exec
privilege exec
global config
interface | user exec: (the initial mode)
privilege exec: enable
global config: config t
interface: interface fa0/0 (or whatever interface) |
| what information can be obtained from the show interface fastEthernet command? | the mac address of outgoing interfaces |
| which is the routing protocol or traffic forwarding that has the lowest overhead or uses the least resources? | static route |