Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
132 Cards in this Set
- Front
- Back
Difference between Simplex, Half-Duplex and Full-Duplex Communication
|
Simplex - One way communication (like listening to a radio)
Half-Duplex - Sends or receives information one at a time (like a Wallie-talkie). Full-Duplex - Sends and receives information simultaneously (like a face to face conversation) |
|
Baseband vs. Broadband
|
Baseband networks have one channel. Ethernet is an example.
Broadband networks have multiple channels, and can send multiple signals simultaneously (like cable tv). |
|
Analog vs. Digital
|
Analog is what our ears can hear, digital is 1's and 0's.
|
|
LAN vs. MAN vs. WAN vs. GAN vs. PAN
|
LAN (Local Area Network) - Usually confined to a building.
MAN (Metropolitan Area Network) - Usually covers a city, campus or office park. WAN (Wide Area Network) - Usually covers multiple cities, states or even countries. GAN (Global Area Network) - GIG is an example of this (It is the DoD's global network PAN (Personal Area Network) - Like Bluetooth |
|
Internet vs. Intranet vs. Extranet
|
Internet - Global collection of peered networks running TCP/IP, providing "best effort service"
Intranet - Privately owned network running TCP/IP. Extranet - Connection between two Intranets, such as a connection between business partners. |
|
Circuit-Switched vs. Packet-Switched Networks
|
Circuit-Switched - A dedicated circuit or channel (portion of a circuit) is dedicated between two nodes. This is what a T1 line is.
Packet-Switched - Data is broken into packets which are sent individually. The packets can choose the best channel to proceed down, and if there is a failure, can proceed down another channel. |
|
Predecessor of the Internet
|
ARPAnet
Created in the early 60's by Defense Advanced Research Projects Agency (DARPA). It was the first use of Packet-Switched technology. |
|
Quality of Service
|
A way to rank information being sent over a network by it's priority. VoIP would receive a higher priority than would eMail being sent.
|
|
SMTP
|
Simple Mail Transfer Protocol
|
|
Layered Design
|
Network models are layered, and one layer does not usually directly effect another layer. For example, changing your PC from a wireless connection to a wired connection, does not affect your web browser.
|
|
Basic description of Network Models and Stacks
|
Network Model - How a network protocol suite operates (i.e. OS or TCP/IP)
Network Stack - Programming for hardware or software to enable use of a Network Model |
|
What is OSI?
|
Open System Interconnection
Abstract. Used as reference point to mark layers within a network. |
|
Name the seven layers of OSI
|
Layer 1: Physical
Layer 2: Data Link Layer 3: Network Layer 4: Transport Layer 5: Session Layer 6: Presentation Layer 7: Application |
|
What was the OSI model formally called?
|
X.200 - Information Technology - Open Systems Interconnection - Basic Reference Model.
|
|
Layer 1: Physical Layer
|
Includes bits, energy which encapsulates the bits (electricity, light, radio waves, etc), and the medium used to carry them (copper or fiber optic cables).
|
|
Layer 2: Data Link... What is it, and what are it's 2 sub-layers?
|
Handles access to the physical layer as well as local area network communication (LLC). Examples would be an ethernet card and it's MAC address, as well as switches and bridges.
Two sub-layers: Media Control (MAC) and Logical Link Control (LLC). MAC touches Layer 1 and LLC touches Layer 3. |
|
Layer 3: Network
|
This is the routing (moving data from a system on one LAN to a system on another. IP addresses and routers liven on Layer 3.
|
|
Layer 4: Transport
|
Packet sequencing, flow control and error detection. TCP and UDP are Layer 4 protocols.
|
|
Layer 5: Session
|
Manages sessions, providing MAINTENANCE on connections. A good way to remember the session layer's function is "connection between applications". Uses Simplex, Half-Duplex and Full-Duplex communication.
|
|
Layer 6: Presentation
|
Presents the data to the application (and end user) in a comprehensible way. This includes data conversion with character sets such as ASCII and image formats such as JPEG, TIFF and GIF.
|
|
Layer 7: Application
|
Web browser, word processor, instant messaging client, etc. Also includes Telnet and FTP.
|
|
Please Do Not Throw Sausage Pizza Away
or... All People Seem To Need Data Processing |
Mnemonic to help recall the layers (1-7) or (7-1)
|
|
What is the formal name of TCP/IP, and how does it relate with OSI
|
Internet Protocol Suite. TCP/IP is simpler than OSI because it only has 4 layers instead of 7.
|
|
Name the 4 TCP/IP layers
|
1) Network Access Layer
2) Internet Layer 3) Host-to Host Transport Layer 4) Application Layer |
|
Network Access Layer (of TCP /IP)
|
Combines the Physical and Data Link layers of the OSI model
|
|
Internet Layer
|
This aligns with the Network layer of the OSI model. Although the OSI layer is called the Network layer, it should not be confused with the Network layer of TCP/IP.
|
|
Host-to-Host Transport Layer
|
Also called the Transport Layer. Connects the Internet Layer to the Application Layer. TCP and UDP are the two transport layer protocols.
|
|
Application Layer (of TCP/IP)
|
Combines layers 5 through 7 of the OSI model (Session, Presentation and Application).
|
|
Encapsulation
|
Takes information form a higher layer and adds a header to it. Each layer's information (data) could be encapsulated to be sent to the next layer.
|
|
PDU
|
Protocol Data Units
|
|
The reverse of Encapsulation (including a description of the process)
|
De-Multiplexing (or De-Encapsulation)
Moving up the stack, bits are converted to Ethernet frames, frames are converted to IP packets, packets are converted to TCP segments, segments are converted to application data. |
|
What is included in TCP/IP, and at what layers?
|
IPv4 and IPv6 (Layer 3)
TCP and UDP (Layer 4) Several protocols at Layers 5-7 including Telnet, FTP, SSH, etc. |
|
MAC Addresses
|
Media Access Control
The unique address of the Ethernet network interface card (NIC). Typically 48 or 64 bits long, with the first 24 bits being the OUI, and the last numbers being the serial number. |
|
OUI
|
Organizationally Unique Identifier
|
|
Producer of OUI's
|
Institute of Electrical and Electronics Engineers (IEEE), Incorporated Registration Authority
|
|
Basics of IPv4 and IPv6
|
Internet Protocol version 4 and version 6
IPv4 uses 32 bit source (192.168.2.2) and IPv6 uses 128 bit (fco1::20c:29ff;feef:1138/64). |
|
8 key fields of an IPv4 Header
|
1) Version
2) IHL: Length of header 3) Type of Service: Precedence of the packet 4) Identification, Flags, Offset: Used for IP fragmentation 5) Time to Live: to end routing loops 6) Protocol: Embedded protocol (UDP, TCP, etc.) 7) Source and Destination IP addresses 8) Optional: Options and padding |
|
MTU
|
Maximum Transmission Unit
Refers to the max size of packet that a network can handle. A typical size is 1500 bytes. |
|
IPID
|
IP Identification Field
Used to re-associate packets that have been broken apart because they are too large. |
|
Flags
|
Determines whether fragmentation is allowed and whether more fragments are coming.
|
|
Fragment Offset
|
Tells where the offset occurs in fragmentation ("Copy this data begninning at offset 1480").
|
|
IPv6 Header (5 fields)
|
1) Version
2) Traffic Class and Flow Label: Used for Quality of Service 3) Payload Length (Length of the data not including the header) 4) Next Header (next embedded protocol header) 5) Hop Limit: to end routing loops |
|
IPv6 configuration of IPv6 addresses
|
Autoconfiguration (no need for static addressing or DHCP).
|
|
Difference between Global and Link Addresses
|
Global is the communication address to the rest of the world.
Link is used for local network communication |
|
What does :: replace in an IPv6 address?
|
Consecutive zeroes
|
|
What are 2 ways in which IPv6 can cause security issues?
|
1) It will automatically configure a link-local address without the need for any other IPv6-enabled infrastructure.
2) ISPs also enable IPv6 service without the customer's knowledge. |
|
Classful Networks
|
The original IPv4 networks (before 1993). Classes A through E. These were inflexible and resulted in the waste of 250 IP addresses.
|
|
Classless Inter-Domain Routing (CIDR)
|
Allows for expansive network sizes beyond the arbitrary amounts of a Classful network.
|
|
RFC (short for Request for Comments) 1918 Addressing
|
Private addresses that are used for internal traffic and do not route through the internet. This allows for reuse of IP addresses across several networks without wasting the scarce IPv4 addresses.
|
|
What are some examples of RFC 1918 addresses?
|
10.0.0.0 - 10.255.255.255 (10.0.0.0/8)
172.16.0.0 - 172.31.255.255 (172.16.0.0/12) 192.168.0.0 - 192.168.255.255 (192.168.0.0/16) |
|
Network Address Translation (NAT)
|
Used to translate IP addresses. NAT allows an RFC 1918 address to communicate with the web.
NAT hides the origin of the packet with the router or firewall acting as the NAT gateway. |
|
What are 3 types of NAT?
|
1) Static NAT - Makes a one-to-one translation between addresses.
2) Pool NAT (Dynamic NAT) - Reserves a group of Public IP addresses to be used and then returned. 3) Port Address Translation (PAT) -Takes a many-to-one approach in taking several private addresses and converting them to one public address. Common solution for homes and small offices. |
|
ARP
|
Address Resolution Protocol - Used to translate between layer 2 MAC addresses and layer 3 IP addresses.
"Who has IP address 192.168.2.140, tell me." |
|
RARP
|
Used by diskless workstations to request an IP address. "Who has MAC address at 00:40:96:29::06:51, tell 00:40:96:29:06:51." RARP is essentially asking, "Who am I?"
|
|
Unicast
|
One-to-one public traffic (such as surfing on the internet) or one-to-all while on a LAN.
|
|
Multicast
|
Uses Class D addresses when used on IPv4. A common multicast use is streaming audio or video.
|
|
Broadcast traffic
|
Broken up into limited broadcast and directed broadcast. Limited is never sent across a router and it's address is 255.255.255.255.
Directed (or net-directed) can be broadcast from a remote network. |
|
Layer 2 Broadcast
|
Reaches all nodes in a broadcast domain (such as a switch).
|
|
Promiscuous Network Access
|
Ability to access all unicast traffic on a network.
|
|
NIDS
|
Networked Intrusion Detection System
Requires promiscuous network access |
|
TCP
|
Transmission Control Protocol
A reliable layer 4 protocol that uses a three-way handshake to create connections over a network. Can reorder segments that arrive out of order, and retransmit missing segments. |
|
Key TCP Header Fields (four of them)
|
20 bytes long and contains a number of fields such as...
Source and Destination port Sequence and Acknowledgement Numbers TCP Flags Window Size (the amount of data that may be sent before receiving acknowledgement). |
|
TCP Ports... What are they and what are the 2 different types?
|
Connects from a source port to a destination port
Reserved port - From 0 to 1023. Requires super user access to open a reserved port. Ephemeral ports - 1024 - 65535. Any user can open one of these as long as they are unused. |
|
IANA
|
Internet Assigned Numbers Authority
|
|
Socket vs. Socket Pair
|
A socket is a combination of an IP address and a TCP or UDP port on one node.
A socket pair describes a connection between two sockets (inbound and outbound) |
|
What are the 8 TCP Flags (with the first 6 being the original ones)?
|
1) URG - Packet contains urgent data
2) ACK - Acknowledge received data 3) PSH - Push data to application layer 4) RST - Reset (tear down) a connection 5) SYN - Synchronize a connection 6) FIN - Finish a connection (gracefully) 7) CWR - Congestion Window Reduced 8) ECE - Explicit Congestion Notification Echo |
|
What are flags primary purpose?
|
Manage congestion (slowness) along a network path.
|
|
What are the 3 steps of the TCP Handshake?
|
1) Synchronize (SYN)
2) Synchronize (SYN) - Acknowledge(ACK) 3) Acknowledge (ACK) |
|
What is an acknowledgement number?
|
The connection begins with a number and then that number is incremented as the message continues. This way, if one side ACK's a wrong number, then the sender knows their was a failure.
|
|
What is a nick name for UDP
|
Send and Pray (since there is no handshake, session or reliability).
|
|
What layer does UDP operate at?
|
Layer 4 (Transport)
|
|
ICMP
|
Internet Control Message Protocol
A helper protocol that helps with error control. Does not know ports, but uses echo request and echo reply with time to live to determine health of transmission. |
|
Ping
|
Echo request followed by Echo reply
|
|
TTL
|
Time to Live
A counter to ensure that a packet gets to Live |
|
Traceroute
|
Determines all of the routers (hops) that are in a path. The TTL drops one level each time a router is hit. The Traceroute learns this series of drops to determine the number or routers.
|
|
Name 9 protocols at TCP/IP Application Layer
|
1) Telnet
2) FTP 3) TFTP 4) SSH 5) SMTP, POP and IMAP 6) DNS 7) SNMP 8) HTTP and HTTPS 9) BOOTP and DHCP |
|
Telnet
|
Terminal emulation over a network.
Weak b/c it provides no confidentiality and limited integrity. |
|
FTP
|
File Transfer Protocol
Used to transfer to and from servers. Also has no confidentiality and integrity Uses control connection port (sent) 21 and data connection port (transferred) 20 |
|
TFTP
|
Trivial File Transfer Protocol
Runs on UDP port 69. A simpler way to transfer files while saving router configurations or "bootstrapping". |
|
SSH
|
Designed as a secure replacement for Telnet, FTP, etc. Provides confidentiality, integrity and secure authentication. Listens on port 22. Currently on version SSHv2.
|
|
SMTP
|
Simple Mail Transfer Protocol
Port 25. Used to transfer email between servers. |
|
POP
|
Post Office Protocol
Port 110. Client-server email access. |
|
IMAP
|
Internet Message Access Protocol
Port 143. Client-server email access |
|
DNS
|
Domain Name System
Gets names when given an IP or visa versa. Uses UDP or TCP port 53. Can be unreliable when using UDP and provides no authentication. |
|
DNSSEC
|
Domain Name Server Security Extensions
Provides authentication and security to DNS by using Public Key Encryption. It does not provide confidentiality. Not widely used b/c of the difficulty with internet public key encryption. |
|
SNMP
|
Simple Network Management Protocol
Used to monitor network devices (interface status, bandwidth utilization, CPU temperature, etc.) |
|
HTTP and HTTPS
|
Hypertext Transfer Protocol and Hypertext Transfer Protocol Secure
Both transfer data via the web. HTTP on port 80 and HTTPS on 443 |
|
BOOTP
|
Bootstrap Protocol
Allows loading an OS via network |
|
DHCP
|
Dynamic Host Configuration Protocol
An improvement on BOOTP. Both BOOTP and DHCP use port 67 (servers) and 68 (clients) |
|
How to reduce electro magnetic interference (EMI) in cabling
|
Twisted pairs reduce this by having one wire carrying data out and one wire receiving data.
|
|
UTP
|
Unshielded Twisted Pair
|
|
What makes a CAT 6 cable different than a CAT 3 cable?
|
Tighter twisting and therefore more dampening. CAT 6 is designed for gigabit networking.
|
|
STP
|
Shielded Twisted Pair
More expensive and rigid, but less susceptible to EMI. |
|
What are the speeds of the various categories of cables?
|
Cat 1: <1 mbps (Analog voice)
Cat 2: 4 mbps (ARCNET) Cat 3: 10 mbps (10baseT Ethernet) Cat 4: 16 mbps (Token Ring) Cat 5: 100 mbps (100baseT Ethernet) Cat 5e: 1000 mbps (1000baseT Ethernet) Cat 6: 1000 mbps (1000baseT Ethernet) |
|
Difference between Coaxial cables and Twisted Pair
|
Coaxial has thicker and better insulation and therefore more resistant to EMI, and allows for higher bandwidth. Thinnet and Thicknet are 2 older types of coaxial cable.
|
|
Fiber
|
Fiber Optic Network Cable.
Uses light to carry more data faster with no EMI when compared with twisted pair or coaxial cable. |
|
Wavelength Division Multiplexing (WDM)
|
Allows fiber to carry multiple signals
|
|
Ethernet
|
Transfers data via frames. Occupies layer 1 (physical medium) and layer 2 (frames). Started as physical bus topology and has progressed to physical star.
|
|
CSMA
|
Carrier Sense Multiple Access
Used to prevent collision with regards to the Baseband Ethernet traffic. |
|
Difference between CSMA/CA and CSMA/CD
|
CSMA/CD is used for systems that can send and receive simultaneously (such as wired Ethernet).
CSMA/CA (Collision Avoidance) is used by those that cannot send and receive simultaneously. CD is superior b/c it detects collisions immediately. |
|
ARCNET and Token Ring
|
ARCNET (Attached Resource Computer Network) and Token Ring are legacy LAN technologies.
Both use tokens to pass network data. Has not collisions, but not as fast and more expensive than Etherrnet. |
|
FDDI
|
Fiber Distributed Data Interface
Legacy LAN technology using rotating rings for fault tolerance. |
|
Bus
|
Connects system in a string. A problem between two devices will result in problems all the way down the string.
|
|
Tree Topology
|
Hierarchical network in which a root node (often a mainframe) feeds branches which divide
|
|
Ring
|
Strings nodes in a ring, so that if you follow the string, you will end up where you started.
|
|
Star Topology
|
Each node is connected to a central device such as a hub or switch.
More cabling is required, but has much better fault tolerance. |
|
Mesh
|
Interconnects network nodes to each other. Used to ensure HA (high availability) so that if one server goes down, there is another that can shoulder the load.
|
|
T1s and T3s
|
T Carriers are US based while E Carriers are Europe based.
T1= 1.5 Megabit circuit that carries 24 64 bit Digital Signal (DS). One T1 carries one DS1 T3= 28 bundled T1s (45 Megabits) |
|
E1 and E3
|
Europe's version of T1 and T3.
Higher bandwidth at E1 vs T1 (2.048 mbs vs 1.5 mbs), but less at the E3 level (34 mbs compared with 45 mbs for T3). |
|
SONET
|
Synchronous Optical Networking
Carries multiple T circuits via fiber optic cable. Uses physical fiber ring for redundancy. |
|
Forwarding Tables
|
Used to tell a bridge which port to send data to.
|
|
Source Routing
|
The necessary routing information is contained in the header of the packet and does not require forwarding tables.
|
|
What is the difference between two LANs connected with a bridge and two LANs connected with a router?
|
Those connected with a bridge are just extended, whereas those connected with a router have formed an inter-network.
|
|
Gateway
|
Software on a device that acts as a type of router, but actually is usually involved in translations between different types of environments. Internetwork Packet Exchange (IPX) is an example.
|
|
3 Firewalls and 2 subtypes
|
1) Packet-Filtering - The simplest and weakest of the firewalls
2) Stateful Firewall - Looks back over it's ACLs to see if it should be allowed. 3) Proxy Firewall - Middleman who checks packages. 3a) Application Proxy - Inspects package up through the application layer. Requires one proxy for each service (FTP, NTP, SMTP, etc). 3b) Circuit-level Proxy - Works at the session layer and is concerned with the source and destination addresses. SOCKS is an example of a circuit-level proxy gateway. |
|
Kernel Proxy Firewall
|
Fifth Generation Firewall
Creates a new virtual network to examine the specific parts of the packet that are necessary. |
|
Dual-Homed Firewall
|
One host facing the internal network and the other facing the external world.
Can also be multihomed |
|
Screened Subnet
|
A secondary firewall inside the initial firewall to create a DMZ
|
|
DNS Pharming Attack
|
An attacker changes the routing IP address to redirect to a malicious site.
|
|
Dedicated Link
|
Leased line or point-to-point link. Connects two destinations via a WAN
|
|
SMDS
|
Switched Multimegabit Data Service
Allows two LANs to communicate via a MAN or WAN. Not used much anymore. |
|
HSSI
|
High-Speed Serial Interface
Interface that connects routers and other physical layer devices to ATM or Frame Relay |
|
SIP
|
Session Initiation Protocol
Relies on 3 way handshake to secure VoIP sessions. |
|
FHSS vs DSSS
|
Frequency Hopping Spread Spectrum uses part of the bandwidth while Direct Sequence Spread Spectrum uses all of the bandwidth.
|
|
8 Wireless standards
|
1) 802.11 - Dictates how wireless clients and their APs communicate.
2) 802.11b - Most common standard today. 2.4 GHz 3) 802.11a - 5 GHz (uses OFDM) 4) 802.11e - Provides for QoS 5) 802.11f - Provides for roaming between APs 6) 802.11g - Provides for faster speed over 802.11b 7) 802.11h - Allows for global 802.11a 8) 802.11i - Incorporates security into the 802.11 protocols |
|
Bluejacking
|
An unsolicited bluetooth message is sent in an effort to get their contact information into your phone.
|
|
WAP
|
Wireless Application Protocol
An industry driven protocol stack. Designed to use limited resources to gain information such as weather, stock quotes, etc. |
|
Encryption of a data sent over a cell phone. Is it End-to-End and why?
|
No. It will be encrypted over the wireless portion of it's journey, but not over the wired portion of the journey.
|
|
Mobile Technology Generations
|
1G: Analog/Voice
2G: Voice with Low speed data 2 1/2G: Higher bandwidth than 2G 3G: Voice and Data with packet-switched technology |
|
What can be compromised if the OS does not have packet forwarding or routing disabled?
|
Dual-homed firewalls
|
|
Protocol
|
A set of rules that dictate how computers communicate over networks
|
|
TKIP
|
Temporal Key Integrity Protocol
Generates random values in wireless encryption. |