Network + Study Guide

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Chapter 1

A topology describes how the part of a whole work together.

Physical topology, or network topology, mostly applies to hardware and describes how computers, other devices, and cables fit together to form the physical network.

Logical topology has to do with the software and describes how access to the network is controlled, including how users and programs initially gain access to the network and how specif resources, such as applications and databases, are shared on the network.

Peer-to-Peer Network Model-the operating system of each computer on the network is responsible for controlling access to its resources without centralized control. The computers, called nodes or hosts on the network, for a logical group of computers and users that share resources. Administration, resources, and security on a computer are controlled by that computer

Client-Server Network Model-(which is sometimes called the client-server architecture or client-server topology) resources are managed by the NOS via the centralized directory database. The database can be managed by one of more servers, so long as they each have a similar NOS installed

Star Topology- all devices connect to one central device, the switch.

bus topology- multiple switches daisy chained together in a single line

starbus topology combines the two: each switch is connected to it's computers via a star topology (also known as hybrid topology)

Ring topology- Seldom used today. Nodes are connected in a ring with one node connecting only to its two neighboring nodes. Slow speed. A node can put data on the ring only when it holds the token.

Name for a PDU or message as it moves from one layer to another

Layer7, Application Layer Payload or data

Layer6 presentation Layer

Layer 5 Session Layer

Layer 4 Transport Layer Segment (TCP) or datagram (UDP)

Layer 3 Network Layer Packet

Layer 2 Data Link layer Frame

Layer 1 Physical 1 Bit

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Chapter 2

A hexidecimal number also known as a hex number is a number written in the base 16 number syste, which uses the 16 numerals 0-9 and A-F

An A(address record) stores the name to address mapping for a host. This resource record provides the primary function of DNS- to match host names to IP addresses using IPv4.

An AAAA (address) record (called a "quad-A record") also holds the name to adrees mapping, but the IP address is an IPv6 type IP address

A CNAME (Canonical Name) record holds alternative names for a host

A PTR (Pointer) record is used for reverse lookups, to provede a host name when you know it's IP address

An MX (mail Exchanger) record indentifies a mail server and is used for email traffic

Network octets- 1.x.y.z to 126.x.y.z ia class A 126 licenses 16 million IP addresses

128.0.x.y to 191.255.x.y 16000 65000 million

192.0.0.x to 223.255.255.x 2 million 254 million

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Chapter 3

Most common routing protocols:see chart

Which protocols function within an automonous system, and which of these protocols communicate between the systems:

Distance Vector: The simplest type of routing protocols; used to determine the best route for data based on the distance to ta destintation. Some distance-vector routing protocols only factor in the number of hops to the destination while others take into account latency and other network traffic characteristics.

Link State:enables routers to share information beyond neighboring routers after which each router can independently map the network and determine the best path between itself and a message's

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Chapter 4

Be able to contrast a broadcast domain and a collison domain. Both types of domains are defined by the group of nodes that transmissions can reach.

Broadcast Domain-Logically grouped network nodes that can communicate directly via broadcast transmissions. By default switches and repeating devices such as hubs extend broadcast domains. Routers and other layer 3 devices seperate broadcast domains.

Collision Domain- The portion of an Ethernet network in which collisions occur if two nodes transmit data at teh same time, Today switches and routers sepereate collision domains.

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Chapter 5

Network Media:

Coaxial Cable- RG6 used for broadband cable interenet service and cable tv for long distances

RG-8 outdated by was used for earliest ethernet networks called thicknet

RG-58 Used in 80's and 90's called thinnet more flexiable easier to handle made of several strands of thin copper

RG-59 Still used for shorter connections when distrubuting video signals from a central reciever to multiple moniters within a building

RG-6 and RG-59 can be terminated with one of two connector types: F connectors and BNC connectors

F connectors attach coaxial cable so that the pin in the center of the connector is conducting the core of the cable. F connectors require the cable has a sold metal core.Mostly used with RG-6 cable

BNC stands for Bayonet Neill-Concelman, a term that refers to both an older style of connection and its two inventors. A BNC is crimped, compressed or twited onto a coaxial cable. It connects to another BNC connector via a tuen lock mechnaism. You can use a BNC copupler to connect to coaxial cables.

10Base2 is another legacy wire used RG-58 cabling that is thinner and most comply was used for 10mbps Ethernet cable.

A crossover cable has the transmit and recieve wires revereed and is used to connect a Pc to a PC a swithc to a switch or Pc to a router.

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Chapter 6

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Chapter 7

RAS Remote Access Service- was used as a dial up connection made by client computers running windows 95, 95, NT and 2000 to connect to a remote network. The remote access server receiving the dial up connection to the network ran windows NT or Windows 2000 this was replaced by RRAS Routing and Remote access service

When PPP is used over an Ehternet network (no matter the connection type) it is known as PPPoE, this may be used to connect a computer to a modem by way of an Ethernet network adapter and patch cable.

Host to Host VPN- two computers create a VPN tunnel directly between them. Both computers must have the appropriate software installed and they don't serve as a gateway to other hosts or their respective networks.

Point to Point protocol syncronizes clocks on a network

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Chapter 8

Types of Firewall

Packet filtering

Packet filtering or network layer (Layer 3) firewalls make decisions based on the source and destination addresses and ports in IP packets. This basic form of firewall protection is really no more than a simple sorting algorithm. Generally they enable you to have some control through the use of access lists. Packet filtering can also often be performed by other network devices such as routers and is generally what you get when you download free firewall software.

Packet filtering works well for small networks but when applied to larger networks can quickly become very complex and difficult to configure. Packet filtering also cannot be used for content-based filtering and cannot, for instance, remove e-mail attachments. This type of firewall has little or no logging capability, making it difficult to determine if it’s been attacked.

Proxy

The more sophisticated proxy or application layer firewalls deal with network traffic by passing all packets through a separate “proxy” application that examines data at an application level.

A proxy firewall doesn’t allow a direct connection between your network and the Internet. Instead it accepts requests and executes them on behalf of the user. For instance, if you’re behind a proxy firewall and type http://www.blackbox.co.uk, the request goes to the firewall, which gets the page on your behalf and passes it to you. This process is transparent to users

This proxy system enables you to set a firewall to accept or reject packets based on addresses, port information and application information. For instance, you can set the firewall to filter out all incoming packets belonging to EXE files, which are often infected with viruses and worms. Proxy firewalls generally keep very detailed logs, including information on the data portions of packets.

Proxy firewalls are slower and require more hardware than packet filtering; however, their greater versatility enables you to enforce tighter security policies.

Stateful inspection

When a firewall is described as stateful inspection, it means that it examines packets at the network layer like packet filtering does but, rather than just applying simple filtering rules to this information, it uses it in an intelligent way to block out unauthorized traffic. It analyzes data to make sure connection requests occur in the proper sequence. This firewall tracks each communications session from start to end and enforces set rules based on protocol, port and source and destination addresses. By maintaining all session data, the firewall can quickly verify that new incoming packets meet the criteria for authorised traffic. Packets that aren’t part of an authorised session are rejected.

Stateful inspection firewalls have the advantage of being both smart and fast.

HybridPacket-based, proxy and stateful inspection used to be distinctly different types of firewalls, but today nearly all modern firewall appliances are hybrids which provide packet-based, proxy and stateful inspection firewalling.

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Chapter 9

CALEA-CALEA (Communications Assistance for Law Enforcement Act) is a United States federal law that enables the government to intercept wire and electronic communications and call-identifying information under certain circumstances -- in particular, when it is necessary in order to protect national security. CALEA originated in the House of Representatives as bill H.R. 4922 and in the Senate as bill S. 2375. CALEA was signed into law by President Clinton on October 25, 1994.

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HIPAA-HIPAA (Health Insurance Portability and Accountability Act of 1996) is United States legislation that provides data privacy and security provisions for safeguarding medical information

PCI DSS-

The Payment Card Industry Data Security Standard (PCI DSS) is a proprietary information security standard for organizations that handle branded credit cards from the major card schemes including Visa, MasterCard, American Express, Discover, and JCB.

SIP-The Session Initiation Protocol (SIP) is a communications protocol for signaling, for the purpose of controlling multimedia communication sessions. The most common applications of SIP are in Internet telephony for voice and video calls, private IP telephone systems, as well as instant messaging over Internet Protocol (IP) networks.

RTP-The Real-time Transport Protocol (RTP) is a network protocol for delivering audio and video over IP networks. RTP is used extensively in communication and entertainment systems that involve streaming media, such as telephony, video teleconference applications, television services and web-based push-to-talk features.

RTCP-The RTP Control Protocol (RTCP) is a sister protocol of the Real-time Transport Protocol (RTP). Its basic functionality and packet structure is defined in RFC 3550. RTCP provides out-of-band statistics and control information for an RTP session.

MPLS-Multiprotocol Label Switching (MPLS) is a type of data-carrying technique for high-performance telecommunications networks. MPLS directs data from one network node to the next based on short path labels rather than long network addresses, avoiding complex lookups in a routing table.

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Chapter 10

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Chapter 11

WAN Topologies- A network that spans a long distance and connects two or more LAN's

Bus-single cable connecting all nodes on network without intervening connectivity devices

Ring- A type of Wan in which each site is connected to two other sites so that the entire WAN forms a ring pattern

Star- a single site acts as the central connection point for several other points. The arrangement provides separate routes for data between any two sites, however if the central connection point fails the entire wan fails.

partial-mesh- a version of mesh topology WAN in which only critical sites are directly interconnected and secondary sites are connected through star or ring topologies Partial mesh wans are less to implement than full-mesh-wans

full-mesh-every sire is directly conencted to every other site. Full-mesh wan's are the most fault tolerant type of WAN.

fiber-An optical fiber cable, also known as fiber optic cable, is a cable containing one or more optical fibers that are used to carry light. The optical fiber elements are typically individually coated with plastic layers and contained in a protective tube suitable for the environment where the cable will be deployed. Different types of cable[1] are used for different applications, for example long distance telecommunication, or providing a high-speed data connection between different parts of a building.

frame relay-Frame relay is a packet-switching telecommunication service designed for cost-efficient data transmission for intermittent traffic between local area networks (LANs) and between endpoints in wide area networks (WANs)

broadband cable

dsl/adsl-Asymmetric digital subscriber line (ADSL) is a type of digital subscriber line (DSL) technology, a data communications technology that enables faster data transmission over copper telephone lines than a conventional voiceband modem can provide. ADSLdiffers from the less common symmetric digital subscriber line (SDSL).

isdn-Integrated Services Digital Network (ISDN) is a set of communication standards for simultaneous digital transmission of voice, video, data, and other network services over the traditional circuits of the public switched telephone network. It was first defined in 1988 in the CCITT red book

atm-Asynchronous transfer mode (ATM) is a switching technique used by telecommunication networks that uses asynchronous time-division multiplexing to encode data into small, fixed-sized cells. This is different from Ethernet or Internet, which use variable packet sizes for data or frames.

dial-up-access a computer system or service remotely via a telephone line.

wimax-WiMAX (Worldwide Interoperability for Microwave Access) is a family of wireless communication standards based on the IEEE 802.16 set of standards, which provide multiple physical layer (PHY) and Media Access Control (MAC) options.

ethernet-a system for connecting a number of computer systems to form a local area network, with protocols to control the passing of information and to avoid simultaneous transmission by two or more systems.

leased lines-A leased line is a private bidirectional or symmetric telecommunications line between two or more locations provided in exchange for a monthly rent. Sometimes known as a private circuit or data line in the UK.

MLPPP-Standards: RFC 1990. Package: ppp. Multi-Link Point to Point Protocol (MP, Multi-Link PPP, MultiPPP orMLPPP) is a method of splitting, recombining, and sequencing data across multiple logical data links.

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Chapter 12

SCADA- Supervisory control and data acquisition- A network that includes software servers and communication channels. SCADA is responsible for acquiring real-time data from physical system and managing the physical system or presenting the data to humans who monitor and manage the system

RTU-remote terminal unit- A device installed at a key location in an industrial system, which can sense attributes of the physical system and convert this analog data to digital data.

PLC-Programmable logic controller- A very small dedicated computer in an industrial system that is capable of converting analog data to digital data. THe PLC works in real time, can control machinery, and is a critical competent of the ICS

ICS- A group of networked computers used to manage a physical system of industrial processes.