Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Computer System > Week 10 - Network Layer > Flashcards

Week 10 - Network Layer Flashcards

1. Routing/Forwarding 2. Router Architecture 3.IP addressing (64 cards)

Start Studying
1
Q

What is the main service provided by the Network Layer?

A

Host-to-host communication service for the Internet.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the key protocol used at the Network Layer?

A

The Internet Protocol (IP).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What kind of service does the Network Layer provide?

A

A Best Effort service — no guarantees for speed, delay, bandwidth, order, or even delivery.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How does the Transport Layer differ from the Network Layer?

A

The Transport Layer provides logical communication between processes, while the Network Layer provides logical communication between hosts.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Where do network protocols run?

A

On all devices, including hosts/end systems and routers.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What does the sender do with Transport Layer segments?

A

The sender encapsulates Transport Layer segments into IP packets.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What does the receiver do with incoming IP packets?

A

The receiver unpacks IP packets and delivers the segments to the Transport Layer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the two main functions of a router?

A

Routing (deciding the path) and Forwarding (moving packets to the next device).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is forwarding in the context of routers?

A

Forwarding is the process of moving packets from the router’s input to the appropriate output.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What component in the router handles forwarding?

A

Forwarding tables are used to determine where packets should be sent next.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is routing in the context of routers?

A

Routing is the process of determining the path a packet should take from source to destination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What component in the router handles routing?

A

Routing algorithms decide the best path and update the forwarding tables accordingly.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What does forwarding do in a router?

A

It uses the Forwarding Table to decide where to send a packet next, locally at that router.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What does routing do in a network?

A

It uses a Routing Algorithm to determine the complete end-to-end path from source to destination.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the relationship between routing and forwarding?

A

Routing builds the Forwarding Table, and forwarding uses it to move packets along the chosen path.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Do routing decisions happen at every router for each packet?

A

No — each packet uses the precomputed forwarding table, not rerunning the full routing algorithm.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is forwarding similar to in real life?

A

It’s like choosing the right exit at a junction during a trip — a local, immediate decision.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is routing similar to in real life?

A

It’s like planning the full road trip from source to destination, including all junctions and roads.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do routing and forwarding work together?

A

Routing plans the full path (like GPS), and forwarding makes the turn-by-turn choices based on that plan.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Which is a per-packet operation: routing or forwarding?

A

Forwarding — each packet is forwarded based on the router’s forwarding table, not replanned each time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What are the two key functions of a router?

A

Running routing algorithms and forwarding datagrams.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the purpose of routing algorithms in a router?

A

To determine the best path through the network (e.g., RIP, OSPF, BGP).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What does forwarding do in a router?

A

It moves datagrams from the router’s input to the appropriate output interface.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Name some common routing algorithms used by routers.

A

RIP, OSPF, and BGP.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
What information does the input port use to determine where to send a packet?
The destination IP address from the IP packet header.
26
Where is the decision-making data stored at the input port?
In the Forwarding Table, stored in the input port’s memory.
27
What is the goal of input port processing speed?
To process packets as fast as they arrive — at line speed.
28
What happens if packets arrive faster than they can be forwarded?
They begin to queue in the input port buffer.
29
Why is queueing at the input port a concern?
It can cause delays or dropped packets if the buffer overflows.
30
What is the function of switching fabric in a router?
It transfers packets from input buffers to the correct output buffer.
31
Why are there different switching fabric architectures?
Because different designs offer various trade-offs in speed, complexity, and cost.
31
How is the switching rate in a router typically measured?
It’s often measured in terms of the line rate (the rate at which packets can be transferred).
32
What is the desirable switching rate for a router with n inputs?
The switching rate should be n times the line rate to efficiently transfer packets from inputs to outputs.
33
What happens when packets arrive at the output port faster than they can be transmitted?
The packets will queue in the output port buffer.
34
How are packets selected for transmission from the output port queue?
A scheduling discipline determines which queued datagram is next for transmission.
35
How does packet loss occur in a router’s output port?
Packet loss occurs when the output buffer fills up due to faster incoming packets than the transmission rate.
36
Where else can packet loss occur in the router besides the output buffer?
Packet loss can also occur in the input buffer if the switching fabric is slower than the input ports.
37
Why do forwarding tables use ranges of IP addresses instead of individual IP addresses?
Because there are billions of IP addresses, using ranges helps make the forwarding tables more efficient and manageable.
38
What is the benefit of using IP address ranges in forwarding tables?
It reduces the size and complexity of the forwarding table while still allowing efficient lookups.
39
What method is used to look up forwarding table entries for a given IP destination address?
Longest Prefix Matching is used to find the best match between the destination IP address and the entries in the forwarding table.
40
Why is Longest Prefix Matching important in forwarding tables?
It ensures that the most specific match (longest prefix) is chosen, improving routing accuracy and efficiency.
41
What is the core responsibility of the Internet Protocol (IP) in the Network Layer?
IP is responsible for packet/datagram formatting, packet handling conventions, and IP addressing.
42
What aspects of communication does the Internet Protocol (IP) manage?
IP manages the structuring of packets, how they are handled during transit, and how addresses are assigned and used for routing.
43
What do IP addresses identify in the context of the Internet?
IP addresses are a 32-bit identifier for hosts or router interfaces, enabling unique identification on the network.
44
How are IP addresses related to router and host interfaces?
Each interface (connection between a host/router and a physical link) is assigned a unique IP address. Routers often have multiple interfaces, while hosts typically have one or two.
45
What defines a subnet in terms of IP addresses?
A subnet consists of all physically connected interfaces (without an intervening router) that share the same IP address prefix.
46
How is an IP address split between the subnet and host parts?
The subnet part is represented by the higher-order bits, and the host part is represented by the lower-order bits of the IP address.
47
What is Classless Inter-Domain Routing (CIDR) and how is it represented?
CIDR uses the format a.b.c.d/x, where x represents the number of bits in the subnet part of the address. The total address is 32 bits.
48
In a CIDR address, how do you calculate the number of bits for the host part?
The host part has 32 - x bits, where x is the number of bits allocated to the subnet part.
49
How is a subnet's IP address determined?
A subnet’s IP address is allocated from its ISP’s address space, with each subnet receiving a portion of the ISP’s available address space.
50
In an example where an ISP has a 24-bit subnet part, how could subnets be allocated?
The ISP could allocate the final three bits of the 24-bit subnet part, allowing for multiple subnets within that address space.
51
What is the purpose of Dynamic Host Configuration Protocol (DHCP)?
DHCP allows hosts to dynamically obtain an IP address from a server upon joining a network, eliminating the need for manual configuration.
52
Why do some IP addresses change over time?
Because DHCP assigns dynamic IP addresses, which can change each time a device reconnects to the network.
53
How does DHCP support address reuse and “plug-and-play” networking?
DHCP assigns IP addresses only while a host is connected, allowing addresses to be reused. Hosts can renew their lease if they wish to keep the same address.
54
What are the 4 main steps of the DHCP address assignment process?
1. DHCP Discover – Host broadcasts to find a server 2. DHCP Offer – Server offers IP configuration 3. DHCP Request – Host requests offered IP 4. DHCP Acknowledge (ACK) – Server confirms and assigns IP
55
Besides an IP address, what additional info can a DHCP server provide?
The first-hop router address, DNS server name/IP, and network mask.
56
Why does the DHCP server provide a network mask to the host?
To inform the host how many bits are in the subnet part of its IP address.
57
How does an ISP get its IP address space?
An ISP gets its IP address space from the ICANN (Internet Corporation for Assigned Names and Numbers).
58
What are the responsibilities of ICANN?
ICANN allocates IP addresses, manages the DNS, assigns domain names, and resolves disputes in the domain naming system.
59
What is the purpose of NAT (Network Address Translation) in IP addressing?
NAT allows multiple local devices to share one public IP address by using different port numbers.
60
What does a router do when performing NAT?
The router modifies the source IP and port for outgoing packets, and translates them back for incoming packets.
61
What is a key benefit of NAT for local networks?
NAT allows all devices to share one public IP, reducing the number of IPs needed and providing flexibility in local IP assignment.
62
How does NAT improve security?
Devices inside the local network are not directly visible or addressable from the outside, making them less exposed to attacks.
63

Computer System (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions