Routing Flashcards

1
Q

Which layer does routing take place?

A

layer 3

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2
Q

What is a router?

A

computer/machine set up to route packets

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3
Q

What does router do?

A

examines packet to see which is best place to send it next to reach the destination

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4
Q

Whats an advantage of routing?

A

traffic between networks massively reduced

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5
Q

What is the store and forward?

A

router fully receives the packet
before then sending it out on the destination network

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6
Q

why does router need memory?

A

to buffer packets as they arrive before sending them out

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7
Q

What happens to data?

A

rewrapped into different layer 2 packets

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8
Q

do networks need to be the same type anymore?

A

no

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9
Q

How does the connection work for router?

A

multiple ways
can be via long point-to-point link

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10
Q

Does router need to be directly connected to destination network?

A

no it can send to second router which is connected to that network instead of direct

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11
Q

Where do layer 3 packets need to be delivered?

A

destination machine (specify both machine and nework for each packet)

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12
Q

why do we need routing table?

A

tells us how to send each packet

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13
Q

What does routing table store?

A

since computer dont need to know whole path we only store the next hop

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14
Q

What is meant by next hop?

A

address of next machine to send it to

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15
Q

What does each routing table do?

A

maps a destination address to the next hop

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16
Q

How does next hop routing work?

A

computer looks up next hop for a particular destination and sends packet to it via network connection

17
Q

What happens if receiving machine isnt destination?

A

it looks up in routing table what the next hop is for destination

18
Q

What is source independence?

A

next hope is entirely dependent on destination not packets source

19
Q

Does routing table contain details for every machine?

A

No for same destination network machines will share the same next hop

20
Q

so what does routing table need to store?

A

network prefix part of address

21
Q

What are default routes?

A

routes that are identical and these are used by default unless there is a more specific route

22
Q

advantage of default routes?

A

reduces size of routing table

23
Q

what should routing table guarantee?

A

Universal, optimal routing

24
Q

How are networks in routing table specified?

A

in terms of IP address on network and netmask

25
Q

What is the network address?

A

prefix part of the IP address

26
Q

What is netmask?

A

specifies which bits of IP are significant

27
Q

How do we check if IP is in particular network?

A

use netmask and AND the destination IP address bit by bit
if IP in network result will be equal to it (dest IP)
so on same local network

28
Q

How is default route specified in routing table?

A

its specified as 0.0.0.0/0
netmask is also 0