CSCE 416: Computer Networking Quiz #1

The two most prevalent tpes of broadband residential access are:

(DSL) Digital Subscriber Line and cable.

Propogation delay is measure by:

2L/R

The IEEE LAN/MAN Standards Committee specifies the:

Ethernet and wireless WiFi standards.

What two types of satellites are used in communications?

Geostationary satellites and low-earth orbiting (LEO) satellites

End systems access the Internet through:

Internet Service Providers (ISPs)

What happens to the data that was previously segmented when it reaches it's destination end system?

It is reassembled into the original data.

If instead the packet switch forwarded bits as soon as they arrive, the total delay would then be:

L/R

Lower tier ISPs are interconnected through national and international upper-tier ISPs such as:

Level 3 Communications, AT&T, and NTT.

End-to-End delay:

N*L/R

(PON Architecture) In the home, users connect to the ___ and access the internet via this home router.

ONT

RFCs define protocols such as:

TCP, IP, HTTP (for the web), and SMTP (for email.)

True or False: In a wireless LAN setting, wireless users transmit/receive packets to/from an access point that is connected into the enterprise's network which is turn is connected to the wired internet.

TRUE (Wireless LAN setting question)

What are some examples of physical media?

Twisted-pair copper wire, coaxial cable, multimode fiber-optic cable, terrestrial radio spectrum, and satellite radio spectrum.

Cable modems divide the HFC network into two channels:

a downstream and an upstream channel.

A socket interface specifies how....

a program running on one end system asks the Internet infrastructure to deliver data to a specific destination program running on another end system.

Link-layer switches are typically used in...

access networks.

The fiber in FTTH is split into individual customer-specific fibers and two competing optical-distribution network architetures that perform this spliting are:

active optical networks (AONs) and passive optical networks (PONs.)

FTTH (fiber to the home) provides:

an optical fiber path from the CO directly to the home.

As with DSL, cable internet access is typically:

asymmetric.

Concerning DSL transmission rates, the downstream and upstream rates are different, and so the access is said to be:

asymmetric.

An optical fiber is a thin, flexible medium that conducts pulses of light, with each light representing a ______.

bit

End systems are analogous to...

buildings.

ISPs provide a variety of types of network access such as:

cable modem or DSL, high-speed local area network access, and mobile wireless access.

Cable internet access requires special modems, called:

cable modems.

Hosts are sometimes divided into two categories:

clients and servers.

Some examples of the different types of communications links are:

coaxial cable, copper wire, optical fiber, and radio spectrum.

End systems are connected together by a network of....

communication links and packet switches.

Unshielded Twisted Pair (UTP) is most commonly used for:

computer networks within buildings, for LANs.

DSL and Ethernet use what kind of wire?

copper

Most servers reside in....

data centers.

(Informally) Clients tend to be....

desktops, mobile PCs, smartphones, etc,.

Concerning cable internet access, because the upstream is also shared, a ___________ is needed to coordinate transmissions and avoid collisions.

distributed multiple access protocol

Radio channels carry signals in the ________ spectrum.

electromagnetic

Internet applications run on....

end systems.

Being a shared broadcast medium means that:

every packet sent by the head end travels downstream on every link to every home nd every acket sent by a home travels on the upstream channel to the head end.

Cable internet access makes use of the cable television company's...

existing cable television infrastructure.

An up and coming technology that provides ever higher speeds than DSL or cable internet access is:

fiber to the home (FTTH.)

The Internet Protocol (IP) specifies the _______ of the packets that are sent and received among routers and end systems.

format

The technique of having a single DSL link appear as if there were three separate links, so that a telephone call and an Internet connection can share the DSL link at the same time is called:

frequency-division multiplexing.

A communication satellite links two or more Earth-based microwave transmitter/receiver, known as:

ground stations.

Physical media fall into what two categories:

guided media and unguided media.

Coaxial cable can be used a:

guided shared medium.

The sending end system segments the data and adds _______ ____________ to each segment.

header bytes

An upper-tier ISP consists of:

high-speed routers interconnected with high-speed fiber-optic links.

Communication links are analogous to....

highways and roads.

Devices hooked up to the internet are called...(laptops, TVs, home security, smart-watches, fridges, etc,.)

hosts OR end systems.

Both fiber optics and coaxial cable are employed with cable internet access and so it is often referred to as:

hybrid fiber coax (HFC.)

Packet switches are analogous to....

intersections.

End systems exchange...

messages.

(Informally) Servers tend to be...

more powerful machines that store and distribute web pages, stream video, relay e-mail, etc,.

Store-and-forward transmission means that the packet switch....

must receive the entire packet before it can begin to transmit the fire bit of the packet onto the outbound link.

Routers are typically used in the....

network core.

A packet switch takes a packet arriving on one of its incoming communication links and forwards that packet....

on one of its outgoing communication links.

(PON Architecture) The splitter combines the optical fibers from the ONTs onto a single, shared optical fiber and then connects this to a ___________ in the telephone company's CO,

optical line terminator (OLT)

(PON Architecture) Each home has a _______, which is connected by dedicated fiber to a neighborhood splitter.

optical network terminator (ONT)

Packets suffer:

output buffer queing delays.

Though it is costly, fiber optics is the preferred long-haul guided transmission media, particularly for:

overseas links.

If an arriving packet finds that the buffer is completely full with other packets waiting....

packet loss will occur.

Each ISP is in itself a network of....

packets switches and communication links.

Each packet switch has multiple links attached to it. For each attached link, the packet switch has an output buffer (also called an output queue), which stores:

packets that the router is about to send.

Packages of information are known as....

packets.

The source breaks down long messages into smaller chunks of data known as:

packets.

Radio channels can....

penetrate walls, require no physical wire, and can potentially carry a signal for long distances.

The access network is a netwok that....

physically connects an end system to the first router (also called an edge router.)

All activity in the Internet that involves two or more communicating remote entities is governed by a ______.

protocol

(PON Architecture) The optical line terminator, OLT:

provides conversion between optical and electricla signals and connects to the internet via a telco router.

Routers need to do what before forwarding?

receive, store, and process the entire packet

In the PON architecture, all packets sent from OLT to the splitter are _________ at the splitter.

replicated

Internet standards are developed by Internet Engineering Task Force (IETF) and their standards documents are called:

requests for comments (RFCs.)

LEO satellites....

rotate around Earth.

The sequence of communication links and packet switches is known as...

route or path.

Two pre-dominant types of packet switches:

routers and link-layer switches

The two most prominent types of packet switches are:

routers and link-layer switches.

One important characteristic about cable internet access is that it is a...

shared broadcast medium.

DSL is designed for ____ distances.

short

Terrestrial radio channels can be classified into what three groups:

short distance, local areas, and wide area.

The residential telephone line carries both data and traditional telephone signals ____________.

simultaneously.

End systems attached to the Internet provide a _____ __________.

socket interface

Most packet switches use:

store-and-forward transmission

Because cable internet is a shared broadcast medium, if several users are simultaneously downloading a video file on the downstream channel....

the actual rate at which aeach user receives its video file will be significantly lower than the aggregate cable downstream rate.

The maximum transmission rate concerning DSL is potentially limited by three things:

the distance between the home and the CO, the gauge of the twisted-pair line, and the degree of electrical interference.

A local area network (LAN) is used to connect an end system to:

the edge router.

Geostationary satellites permanently remain above the same spot on Earth and because of this....

the huge distance introduces a substantial propagation delay.

After ethernet users connect to the ethernet switch, the ethernet switch then connects into:

the internet.

Queing delays are variable and depend on:

the level of congestion in the network.

A residence typically obtains DSL Internet access from...

the same local telephone company that provides its wired local phone access.

The data rates that can be achieved by unshielded twisted pir (UTP) depend on:

the thickness of the wire and the distance between transmitter and receiver.

Propogation delay is:

the time it takes for the bits to travel across the wire at near the speed of light.

Applications are said to be distributed applicates since...

they involve multiple end systems that exchange data wth each other.

Different communication links can transmit data at different __________ _________, measured in bits/second.

transmission rates

Packets are analogous to...

trucks.

DSL mode uses the existing telephone line, which is:

twisted pair copper wire.

What is the dominant solution for high-speed LAN networking?

twisted-pair

Ethernet users use _______ to connect to an ethernet switch.

twisted-pair copper wire

The least expensive and most commonly usesd guided tranmission medium isL

twisted-pair copper wire.

Coaxial cable cosists of:

two copper conductors.

With guided media....

waves are guided along a solid medium.

With unguided media....

waves propogate in the atmosphere and in outer space, such as in a wireless LAN or a digital satellite channel.

Cellular access technologies use....

wide-area radio channels.

Many homes combine broadband residential access (that is, cable modems or DSL) with:

wireless LAN technologies.