cisco labs 2

Question 1

what is the difference between ping and traceroute in networking

Answer 1

ping is used to test whether a device is reachable and how long it will take to send and receive data while traceroute shows the exact route taken to reach the device. traceroute can still be used even if a ping is unsuccessful to show where the connection gets dropped.

Question 2

what does CIDR notation 0.0.0.0 0.0.0.0 mean in networking

Answer 2

defines an ip block containing all ipv4 addresses
it also sets the gateway of last resort on a router, similar to ip default-gateway

Question 3

how to configure rip routing protocol on a router

Answer 3

router rip
network address(without subnet/wildcard)
no auto-summary

Question 4

which commands is used to debug a routing protocol like rip

Answer 4

debug ip rip

Question 5

what is a multicast address

Answer 5

group of receivers/computers with ip address range from 224.0.0.0 to 239.255.255.255(class D)

Question 6

difference between unicast, multicast, broadcast, anycast and incast

Answer 6

unicast is one-to-one, multicast one to may, broadcast is one to all, anycast is one to any, and incast is many to one.

Question 7

what is administrative distance in networking

Answer 7

first criterion that a router uses to determine which routing protocol to use if two or more protocols provide route info for same destination

Question 8

what is the difference between wildcard mask and subnet mask

Answer 8

wildcard mask is the inverse of the subnet mask it is used in ospf and eigrp setup of the network command

Question 9

what happens if a route source has an administrative distance of 255

Answer 9

router dismisses that route and does not install it on its routing table

Question 10

what is a floating static route

Answer 10

it is a backup route configured with a higher administrative distance than the primary route and therefore will not be in the routing table until the primary one fails

Question 11

difference between ospf and rip

Answer 11

rip allows max of 15 hops while no restriction on hop count for ospf
rip has ad of 120 while ospf has ad of 110
rip uses udp while ospf uses ip
rip calculates metric using hop count while ospf uses bandwidth
rip has multicast address of 224.0.0.9 while ospf has multicast of 224.0.0.5 and 224.0.0.6

Question 12

what is the difference between metric and administrative distance

Answer 12

AD is used to choose between multiple paths learned via different routing protocols while metric is used to choose between multiple paths learned with the same routing protocol

Question 13

what is the difference between advertised distance and feasible distance in eigrp

Answer 13

advertised distance your neighbor tells you how far it is for him to reach the destination and feasible distance is total distance to the destination

Question 14

will two routers on different rip versions experience connectivity

Answer 14

no, they have to be on the same version of rip

Question 15

can you modify administrative distance of a standard routing protocol

Answer 15

It will make the protocol a static route depriving it its dynamic capability. Modification of administrative distance to be done only on static routes

Question 16

what is a loopback interface and what is it purpose in networking

Answer 16

a virtual interface that is always up and reachable as long as at least one of the ip interfaces is operational. used for debugging since its ip can always be pinged.

Question 17

why do loopback interfaces go up immediately without having to be manually “no shut” like other interfaces

Answer 17

because the main purpose of a loopback interface is to stay up and be reachable.

Question 18

which commands configure a loopback interface

Answer 18

int loopback 0
ip add 10.0.0.0 255.255.255.255

Question 19

does a loopback interface have a mac address?

Answer 19

no, because it is a virtual interface.

Question 20

why are loopback interfaces configured with /32

Answer 20

because you cannot have more than one interface in a router in the same subnet. using /32 ensures the loopback interface cannot share the subnet with another interface in its subnet.

Question 21

what is the use of a passive-interface command in networking like eigrp

Answer 21

it stops the router sending and receiving hello packets on the interface where it’s configured.

Question 22

why is it best practice to have loopback interfaces as passive

Answer 22

to ensure it is advertised by the routing protocol but not waste resources sending and listening to its hello packets when there’s never going to be a router connected to it(its interface)

Question 23

how to prove eigrp is working in connected routers

Answer 23

show adjacencies using(show ip eigrp neighbors)

Question 24

what will happen if you use a wrong wildcard mask in eigrp

Answer 24

routers not in that wildcard mask subnets will not form adjacencies. It is crucial to confirm you have the right wildcard mask

Question 25

how do you stop advertising a particular subnet in a network using routing protocol eg rip

Answer 25

you make the interface with that subnet passive inside the routing protocol configs eg
router rip
passive-interface f1/1
network 203.0.113.0

Question 26

what is default-information originate used for in routing protocols

Answer 26

it advertises the default route to its neighbors if present in the routing table. eg ip route 0.0.0.0 0.0.0.0 203.0.113.2 is injected to the routing protocol and neighbors learn of that route that way