05 IS 2639 - Lesson 5: Network Protocols

Protocols

Protocols

Rules and procedures for communication and behavior

Protocol Suite or Protocol Stack

A set of protocols works cooperatively it is called a ?

Transmission Control Protocol/Internet Protocol (TCP/IP)

Most common protocol stack

Application Layer Protocol HTTP

Formats a request for your home page by using the?

Data

unit of information the application layer works with is simply?

Transport-Layer protocol (TCP)

The Application-Layer Protocol HTTPpasses the request down to the _______

Segment

The unit of Information the transport layer works with is called a?

Internetwork Layer Protocol

TCP passes the segment to the ___________

Application Layer

provides network services to user applications that access network resources

• Access by applications to network services

• Client/Server Data Access

• Name Resolution

• Dynamic Address Assignment

• Authentication/User Logon

• Data Formatting and Translation

Application Layer provides these functions:

True

True or False

Originally, HTTPs main purpose was to transfer static web pages written in HTML

TCP

HTTP uses ____ as its Transport-Layer Protocol

Post Office Protocol Version 3 (POP3)

used to download incoming messages from email servers to local desktops, it uses TCP port 110

Internet Message Access Protocol Version 4 (IMAP4)

used to manage email messages locally yet stores them on a server, uses port 143

Simple Mail Transfer Protocol (SMTP)

standard protocol for sending email over the Internet, uses TCP port 25

File Transfer Protocol

a client/server protocol used to transfer files and manage files across network

Users sending control commands

FTP uses TCP ports 20 and 21, port 21 is for?

Transferring file data

FTP uses TCP ports 20 and 21, port 20 is for?

True

True or False

FTP is not a secure protocol

Trivial File Transfer Protocol

a simple protocol for transferring files

has little file management capability

it uses UDP port 69

Server Message Block (SMB)

• protocol Windows file and printer services use to share resources between Windows computers.

• Almost exclusively in a private network instead of across the Internet

• Uses TCP port 445

Remote Desktop Protocol

used to access a Windows computer remotely by using the Windows GUI

uses TCP port 3389

Telnet and Secure Shell (SSH)

used to connect to a device across a network via a command-line interface

Simple Network Management Protocol (SNMP)

used to monitor and manage network devices and gather statistics about network traffic

True

True or False

A drawback of using TCP/IP in a large network is keeping track of assigned addresses and to which machine they are assigned

Dynamic Host Configuration Protocol (DHCP)

used to automatically assign IP addresses as needed

DHCP server, Broadcast message

When a computer is turned on, it requests an IP address from a server that is configured as a _____, then the request is sent in the form of a ______

Lease

The server assigns an address for a specific amount of time called?

IP Address Scope

a range of IP addresses the server leases to clients

Scope Options

IP settings such as default gateway, DNS servers, a domain name, and other options

Reservations

an IP address tied to a particular MAC Address

Exclusions

one or more IP addresses excluded from the IP address scope

DHCP Server Service

runs in the background and listens on UDP port 69 for IP address requests

Computers can easily be moved and request new IP configuration from DHCP server on the new segment

Benefit of using DHCP

True

True or False
DHCP servers are usually located on the same network and DHCP messages are short

DHCPDiscover

client announces to the network that it’s looking for a DHCP server

DHCPOffer

server replies and offer the client an IP address for lease

DHCPRequest

client wants the offered IP address

DHCPack

server acknowledges the transaction and the client can now use the IP address

DHCP client software

runs as a service that starts when the computer starts

Domain Name System (DNS)

A name-to-address resolution protocol that keeps a list of computer names and their IP addresses

True

True or False

Using DNS, a user can use a computer’s name instead of using it’s IP address

True

True or False

DNS uses UDP because DNS messages usually consist of a single packet of data

Treelike Hierarchy

DNS is organized as a ?

Fully Qualified Domain Name (FQDN)

When you put all the names of a branch together, separate by periods, you have the_________

Top-Level Domains

Are organized into categories such as commercial (.com), nonprofit organizations (.org), government (.gov), or country of origin indicated by two-letter code

Second-Level Domain

usually the name of a company or institution

Subdomain Level

optional and can consist of names separated by a period

Host Level

represents individual computers hosting network services

Second-Level, Top-Level Domain, Subdomain

A zone is named by using the ______ and ________ and _______

DNS Server Database

contains a list of IP Addresses that point to root servers

Resolver Cache

• DNS clients in most OSs maintain a DNS cache

• This cache stores name and IP address pairs and other data for names that have been resolved recently

DNS client

responsible for communicating with a DNS server to resolve computer and domain names to IP addresses

Resolver

DNS client is referred to as a?

One Address

An OS must be configured to use DNS and needs at least _____ of a DNS server that it can query

Preferred DNS server

first DNS server configured is called?

Alternate DNS Server

Second DNS server is called?

True

True or False

DNS servers require a domain in addition to a computer name

Primary DNS Suffix

The default domain appended to DNS lookups is called?

Windows support Dynamic DNS

allows computers and other devices to contact their primary DNS server whenever their name or address changes

DNS zones

a database of primarily hostname and IP address pairs

Resource Records

the data contained in a zone

Cache

results of queries are cached so that if the same query occurs again, local DNS server can respond without having to contact another server

Root Hints

file containing a list of all IP addresses of Internet root servers

DNS Server Services

Runs in the Background and listens for DNS queries on UPD port 53

True

True or False

DNS servers can be configured with no zones at all

Caching-only server

DNS servers can be configured with no zones at all, this is a configuration called a ______

Transport-Layer Protocols

Used with most application-layer protocols because they:

• Supply a header field to identify the Application layer

• Provide reliability and flow control for applications that typically transfer a large amount of data

Transmission Control Protocol (TCP)

connection oriented and designed for reliable transfer of information in complex internetworks

User Datagram Protocol (UDP)

connectionless and designed for efficient communication of generally small amounts of data

• Work with segments (TCP) or Datagrams (UDP)

• Provide a means to identify the source and destination applications involved in a communication

• Protect data with a checksum

Both TCP and UDP perform the following tasks:

Segments, Datagrams

TCP works units of data called _____ and UDP works with units of data called ____

Internetwork-Layer Protocol

With incoming data, the __________ de-encapsulates the packet and forwards the resulting segment or datagram to the Transport-Layer protocol

Port Numbers

• TCP and UDP use _______ to specify the source and destination Application-Layer Protocols

• Are 16-bit values assigned to specific applications running on a computer or network device

Internet Assigned Numbers Authority

assigns a dedicated port number to every well-known network service

True

True or False

If an application requires reliable data transfer, it uses TCP as the Transport-Layer protocol

• Establishing connection

• Segmenting large chunks of data

• Ensuring flow control with acknowledgements

TCP provides reliability by using these features that aren’t available in UDP:

acknowledgement-synchronization (ACK-SYN) or reset connection (RST) segment

When the server receives the SYN segment, it responds by sending either an ______ or a ______

RST

An ____ is sent when the server refused the request to open the session

ACK-SYN

If an _____ is returned, the client completes the three-way handshake by sending a ACK segment back to the server

Flow Control

prevents a destination from becoming overwhelmed by data, resulting in dropped packets

Window Size

TCP establishes a maximum number of bytes, called the _____, that can be sent before the destination must acknowledge the receipt of data

Internetwork Layer

• where administrators usually do the most network configuration

• Where the IP protocol operates and is the heart of the TCP/IP protocol suite

1. Defines and Verifies IP addresses

2. Routes packets through an internetwork

3. Resolves MAC Addresses from IP addresses

4. Delivers packets efficiently

The internetwork layer is responsible for four main tasks:

• Identify a network device at the internetwork layer

• Identify the network on which a device resides

IP addresses are used for two main purposes:

True

True or False

When a device receives an IP packet, it compares the destination IP address with it’s own:

• If it matches or is a broadcast, the packet is processed

• It it does not match then it is discarded

• IPv4

• IPv6

• ARP

• ICMP

• IPsec

Some of the most commonly used Internetwork-layer protocols:

IP

IPv4 is also known as ___

IPv4

Most common version in networks and the first version that was in widespread use

34-bit dotted decimal

IPv4 defines a ______ IP address

1. Version

2. Time to Live

3. Protocol

4. Checksum

5. Source and Destination Address

Important Fields in an IP Packet

Internet Protocol Version 6

Uses a different format for IP addresses than IPv4

Can run alongside IPv4 without needing to change the Transport Layer or Network Access Layer

• Larger address space

• Hierarchical address space

• Autoconfiguration

• Built-in Quality of Service Support

• Built-in Support for security

• Support for mobility

• Extensibility

Improvements and changes from IPv4

Address Resolution Protocol (ARP)

used to resolve a logical (IP) address to physical (MAC) address

Internet Control Message Protocol

used to send error, status, and control messages between systems or devices

a specialized IP packet with its own header

ICMP echo packets

The ping program uses _________ to request a response from another computer or to verify whether it is available for communication

Indicates whether the host is reachable and how long the message’s round trip from sender to receiver took

Ping Program

The _____ uses ICMP echo packets to request a response from another computer or to verify whether it is available for communication

Tracert Program

The _____ uses ICMP echo packets to determine the route a packet takes through an internetwork

Internet Protocol Security

works with IPv4 to ensure secure delivery of packets

Authentication and Encryption

Internet Protocol Security provides security by using _________ and _________