OSI Model & Networking Basics

• Layer 6 of the OSI model is the Presentation layer.

Physical Layer

• Hubs and network cabling reside at the physical layer of the OSI model.

MAC Addresses

• A MAC address is 48 bits long.

Data Link Layer

• The Data Link layer of the OSI model is divided into two sublayers.

Session Layer

• The Session layer of the OSI model opens and closes conversations between applications.

MAC (Physical) Addresses

• A MAC address is also known as a physical address.

NIC Functions

• A NIC utilizes network protocols for data transfer between the PC and the network.

Router Function

• Routers function at the Network layer of the OSI model.

Transport Layer

• The Transport layer of the OSI model resends packets that were not received in good order.

Physical Addressing

• Physical addressing takes place at the Data Link layer in the OSI model.

Connecting Subnets

• A router connects subnets.

Physical Layer Data Units

• The data unit used at the OSI physical layer is a bit.

OSI Model Layers

• The OSI model contains 7 layers.

Frame Data Capacity

• Frames in most wired networks hold at most 1500 bytes of data.

Application Layer

• OSI layer 7 is also known as the Application layer.

OSI Model

• One benefit of understanding the OSI seven-layer model is using it as a primary tool for troubleshooting networks.

Long Distance Transmission

• Fiber-optic cable works best for long-distance transmissions.

Fiber-Optic Cabling

• Two fibers are often connected together to create duplex fiber-optic cabling.

Electromagnetic Interference (EMI)

• Unshielded twisted pair (UTP) cable suffers from electromagnetic interference (EMI).

Coaxial Cable

• Coaxial cable has a central conductor wire surrounded by insulating materials and placed inside a braided metal shield.

Three-Tier Hierarchical Model

• The Access/Edge layer in the three-tier hierarchical model network architecture facilitates traffic between end devices and the rest of the network.

Network Backbone

• The Core layer is considered the backbone of a network in the three-tier model.

Cabling Installations

• Most new cabling installations use Cat 6 because most networks can run at speeds of up to 1000 Mbps.

Wired Networks

• The 8P8C connector is currently used in wired networks, but commonly referred to as RJ-45.

UTP Cabling

• Cat 5e is the minimum category rating of UTP cabling needed for a network that runs at 1000 Mbps.

Coaxial Cable Use

• The primary use of coaxial cable in networking today is connecting a cable modem to an Internet service provider (ISP).

Network Architecture

• The Access/Edge layer in the three-tier hierarchical model network architecture facilitates traffic between end devices and the rest of the network.

Plenum

• Plenum refers to the space between the acoustical tile ceiling in an office building and the actual concrete ceiling above.

10BASE-T

• The "10" in 10BASE-T means maximum speed of 10 Mbps.

Start Frame Delimiter

• The start frame delimiter is 1 byte long.

Root Guard

• Root guard will move a port into a root-inconsistent state if BPDUs indicate another switch is trying to become the root bridge.

Fiber-Optic Cabling Advantage

• Fiber-optic cabling offers a greater maximum distance compared to other types.

10BASE-FL Standard

• The 10BASE-FL standard specified fiber-optic cabling.

Ethernet Frame Preamble

• The preamble of an Ethernet frame includes a 7-byte series of alternating ones and zeroes followed by a start frame delimiter.

10BASE-T "BASE"

• In a specification such as 10BASE-T, the word "BASE" identifies signaling type.

Ethernet Frame Fields

• A basic Ethernet frame contains nine fields.

Ethernet Frame Size

• The minimum size of an Ethernet frame is 64 bytes.

Wired Network Standards

• The 802.3 working group defines wired network standards that share the same basic frame type and network access method.

Ethernet Frame Data Portion

• The data portion of an Ethernet frame on an IP network includes IP addresses of the source and destination systems.

RJ-45 Connector Pins

• An RJ-45 connector has eight pins.

1000BASE-T Network

• The maximum cable length on a segment of a 1000BASE-T network is 100 meters.

10GBASE-SW "W"

• The "W" in the standard 10GBASE-SW stands for SONET/WAN signaling.

Fast Ethernet

• Fast Ethernet refers to the 100-Mbps standards.

High-Speed Fiber Network

• SONET was already in place for wide area networking (WAN) before the IEEE developed 10 GbE Ethernet standards.

Ethernet Cabling for High Interference

• A technician is most likely to use fiber-optic cabling when installing Ethernet cabling in areas with high electrical interference.

10 GbE Twisted Pair

• The IEEE standard for 10 GbE running on twisted pair cabling is 10GBASE-T.

1000BASE-SX Connector

• The most common connector used in a 1000BASE-SX network is LC.

Ethernet in High Interference Areas

• When installing Ethernet cabling in areas with high electrical interference, fiber-optic is most likely used.

10GBASE-SR "R"

• The "R" in the standard 10GBASE-SR stands for LAN signaling.

Fiber-Optic Laser Signals

• The different colors of the laser signals transmitted over fiber-optic cables feature different wavelengths.

Intermediate Distribution Frame

• The telecommunications room, technically called the intermediate distribution frame (IDF), is where all the horizontal runs from all the work areas come together.

Demarcation Point

• The physical location where connections come in from the outside world is known as the demarcation point (demarc).

Patch Panel

• The most commonly used type of patch panel currently in use is the 110 block.

Structured Cabling Network

• The essential ingredients for a successful basic structured cabling network are a telecommunications room, horizontal cabling, and a work area.

Patch Panel Definition

• A patch panel is a box with a row of ports in front and permanent connections to horizontal cabling in the back.

Horizontal Cabling

• Cables that run from the telecommunication room to the computers are referred to as the horizontal cabling.

Responsibility of Business Owner

• The box where the responsibility of the business owner begins is referred to as the demarcation point (demarc).

IPv4 Digits

• There are 32 binary digits in an IPv4 address.

HTTP Web Severs

• HTTP Web servers use port 80.

IPv4 Decimal Value Range

• The range of decimal values in each of the four groups of an IPv4 address is 0 to 255.

Web Communication Protocol

• Web servers and Web browsers use HTTP to communicate.

Subnet Hosts

• Subnet hosts is calculated using: 2x – 2, where x represents the number of zeroes in the subnet mask.

Class C Network Blocks

• A Class C network block uses the first three octets to define only the network ID.

IP Address Class

• If the first decimal value of an IP address is between 128 and 191, the network belongs to Class B.

Connection-Oriented Protocol

• TCP is a connection-oriented protocol.

Unicast Packet Sending

• Unicast allows one computer to send a message directly to another.

Broadcast Packet Sending

• Broadcast allows every computer on the LAN to hear the message.

DNS and DHCP Protocol

• DNS and DHCP use UDP.

Private IP Address

• 10.164.19.5 is a private IP address.

Loopback Command

• The command "ping 127.0.0.1" tells a device to send packets to itself.

Multicast Packet Sending

• Multicast allows a single computer to send a packet to a group of interested computers.

Apple Network Protocol

• Apple systems today use TCP/IP.

Dynamic IP Addressing

• Dynamic IP addressing via Dynamic Host Configuration Protocol (DHCP) automatically assigns an IP address whenever a computer connects to the network.

Internet Protocol Layer

• The Internet Protocol corresponds to the Network layer.

Valid Host IP Address

• 192.168.4.2 is a valid IP address for an individual host.

Internet Communication Protocol

• Border Gateway Protocol (BGP-4) is used on the Internet for communication between Autonomous Systems.

Network Route Tool

• Traceroute records the route between any two hosts on a network.

Cisco Proprietary Protocol

• EIGRP was originally Cisco's proprietary protocol.

Cisco Operating System

• Cisco's proprietary operating system is called Cisco IOS.

NAT

• Static NAT maps a single routable IP address to a single machine, enabling access from outside the network.

Obsolete Protocol

• RIPv2, adopted in 1994, is now considered obsolete except for small, private WANs.

Routing Table Gateway Value

• 0.0.0.0 routing table gateway value indicates that there is no gateway needed for a network ID.

Bandwidth

• Bandwidth refers to the ability of one connection to handle more data than others.

Network Management Software (NMS)

• NMS is used by an administrator to manage many routers and provide an overall view of the network.

Dynamic NAT

• Dynamic NAT allows many computers to share a pool of routable IP addresses that number fewer than the computers.

NAT Connections

• Port address translation (PAT) typically handles the one-to-many connections form of NAT.

Enterprise Internal Networks

• OSPF routing protocol is the choice in most large enterprise's internal networks.

Maximum Transmission Unit

• Maximum transmission unit is used to determine the largest frame a particular technology can handle.

Router Destination Determination

• A router determines where an incoming packet should go by looking at the packet's destination IP addresses.

Interior Gateway Protocols (IGPs)

• Networks within an AS communicate with Interior Gateway Protocols (IGPs).

Hop

• Hop refers to the passage of a packet through a router.

Exterior Gateway Protocol (EGP)

• The protocol used by Autonomous Systems to communicate with each other is an Exterior Gateway Protocol (EGP).

TFTP Port

• TFTP uses UDP port 69.

Endpoint

• Endpoint refers to session information stored by a computer on one side of a session.

Registered Ports

• Registered ports have a number in the 1024 to 49151 range.

Established Port Status

• An established port describes the status of a port that is part of an active, working endpoint pair.

Connection-Oriented Communication

• Connection-oriented is when two computers first acknowledge each other, communicate, & end by closing the communication.

Session

• Session is used for any single communication between a computer and another computer.

Ping Message

• If you ping a device and no echo reply comes back before the default time, ping will respond with a "request timed out" message.

ICMP Operation

• ICMP works at Layer 3 to deliver connectionless packets.

Three-Way Handshake Protocol

• TCP involves a three-way handshake.

File Transfers

• TFTP is popular for moving files between computers on the same LAN.

IGMP Group Range

• An IGMP multicast group is assigned an address in the Class D range.

Telnet Port

• Telnet runs on TCP port 23.

Well-Known Port Numbers

• The port numbers in the range of 0 to 1023 are well-known port numbers.

TCP/IP Application

• Web servers use port 80.

TFTP Transport Layer Protocol

• Trivial File Transfer Protocol (TFTP) uses UDP for its Transport layer protocol.

Dynamic Ports

• A Web client's source port number is classically assigned as dynamic ports.

DNS Problem

• Ping works with the IP address but not the name associated with that address, that confirms a DNS problem.

Top-Level Domain Servers

• Top-level domain servers are the DNS servers just below the DNS root.

DNS Naming Convention

• In the DNS naming convention, each name is separated by a period (.).

DNS Root Servers

• DNS root servers delegate to domain-specific name servers.

Generic TLDs

• ICANN has added hundreds of generic TLDs, such as .biz and .rodeo.

Internet Hosts

• IP addresses must be unique for hosts on the Internet.

DNS Tree Record

• An NS record points to the server that holds the records (zone) for a part of the DNS tree.

DNS Testing

• Ping is helpful when testing DNS.

FQDN Sequence

• In the DNS naming convention, the correct sequence for writing a fully qualified domain name (FQDN) is host.domain.root.

Top-Level Domain Name

• .com is an original top-level domain name

DNS Server Port

• DNS servers primarily use UDP port 53.

DNS Resolver Cache

• DNS resolver cache keeps IP addresses already resolved.

NetBIOS Broadcasting

• A computer using NetBIOS broadcasted its NetBIOS name along with its MAC address when booted up.

Linux DNS Server

• The most popular DNS server used in UNIX/Linux systems is called BIND.

Windows DNS Server

• Windows DNS server is the default resolver and name server for Active Directory.

FQDN

• Part of a fully qualified domain name (FQDN) is the host name.

Secure Data Transfers

• Secure Copy Protocol (SCP) enables secure data transfers between two hosts.

Ciphertext

• Ciphertext refers to the result of running plaintext through a cipher algorithm using a key.

Authorization

• Authorization defines what an authenticated person can do with data.

Asymmetric-Key

• An asymmetric-key algorithm is used when two different keys, one to encrypt and one to decrypt, are used in encryption.

Common Block Cipher

• Advanced Encryption Standard (AES) is the most-common block cipher and is very fast.

Encryption

• Encryption means to scramble data so that bad guys cannot read it but the intended recipient can descramble it.

HTTPS Connections

• A good certificate exchange is needed for HTTPS connections.

Protection Applications

• Network access control (NAC) defines a newer series of protection applications that combine features traditionally done by separate applications.

Authentication, Authorization, Accounting

• RADIUS offers authentication, authorization, and accounting.

Authentication/Encryption Protocol Suite

• IPSec is an authentication and encryption protocol suite at the Network layer of the OSI model.

Cryptographic Hash Functions

• Cryptographic hash functions are commonly used for verifying file integrity.

Dedicated File Server

• Network attached storage (NAS) is a type of dedicated file server used in many networks.

Standardized File Type

• A certificate refers to a standardized type of file that includes a public key and the digital signature of a trusted third party.

Network Query/Change Protocol

• LDAP is the protocol that programs use to query and change a database used by the network.

Cipher Formula

• Algorithm refers to a cipher's underlying mathematical formula.

Port Aggregation

• Another name for port bonding is port aggregation.

VLAN Trunking Protocol States

• Transparent, server, and client are the three states that can be applied to switches using VLAN Trunking Protocol (VTP).

Segmenting Physical Network

• A virtual local area network (VLAN) enables segmentation without additional hardware.

IDS Mode

• Promiscuous mode allows an intrusion detection system (IDS) to inspect a copy of every packet on a network.

DHCP Relay

• Cisco uses IP helper to implement DHCP relay.

Cisco Aggregation Protocol

• Port Aggregation Protocol (PAgP) is the Cisco protocol for accomplishing aggregation.

Switch Port Configuration

• A trunk port on a switch carries all traffic, regardless of VLAN number, between all switches in a LAN.

VLAN Naming

• A number is typically appended to the word "VLAN" to give a VLAN its name.

Trunk Port Traffic

• The VLAN ID a trunk port associates untagged traffic with its native VLAN.

Managed Switch Configuration

• A managed switch needs an IP address for network configuration.

Switch Data Copy

• Port mirroring is the capability of a switch to copy data from any or all physical ports on a switch to a single physical port.

Server Cluster Creation

• Load balancing refers to making servers look like a single server, creating a server cluster.

Content Switches

• Layer 7 supports content switches.

Connecting Switches

• IEEE 802.1Q trunk standard enables you to connect switches from different manufacturers.

Subnets From Class B

• You can create 1024 subnets if you borrow 10 bits of a Class B network.

85 in Binary

• 85 in binary is 01010101.

Network ID

• 160.160.160.0 /28 and 160.160.160.0 /20 are network IDs.

Subnets From Class C

• You can create 32 subnets if you borrow 5 bits of a Class C network.

10101010 to Decimal

• The binary number 10101010 is 170 in decimal.

Subnet Mask Prefix

• A network with a subnet mask of 255.255.255.240 would have a /28 prefix.

Number of Host Bits

• If you needed a network that would provide for 20 hosts, you would have to have 5 host bits.

Host Range

• The host range for 192.168.32.32 /30 is 192.168.32.33 - 192.168.32.34.

Valid Network Host

• 192.168.24.27 with a subnet mask 255.255.255.248 is a valid host on network 192.168.24.0 /29.

/29 Increment

• The increment of a /29 is 8.