Monday, April 13, 2015

Common Network Protocols - CompTIA A+ 220-801: 2.4

DHCP (Dynamic Host Configuration Protocol)
  • Automated configuration of IP address subnet mask and other options.
    • Requires a DCHP server
      • Server, appliance, ect
  • Dynamic
    • IP addresses are assigned in real time from a pool.
    • Each system is given a lease and must renew at set intervals
  • Static
    • Addresses are assigned by MAC address in the DCHP server
    • Quickly readdress serv ers from one location
DNS (Domain Name Services)

  •  Converts names to IP addresses
  • These are very critical resources
    • IF DNS isn't working, you're not working.
  • Protocol for reading and writing, directories over an IP network.
    • An organized set of records, like a phone directory
LDAP (Lightweight Directory Access Protocol)

  • Protocol for reading and writing directories over an IP network
    • An organized set of records, like a phone directory.
  • X.50 specification was written by the international Telecommunications Union (ITU)
    • They know directories!
  •  DAP ran on the OSI protocol stack
    • LDAP is lightweight, and uses TCP/IP (tcp/389 and udp/389)
  • LDAP is the protocol used to query and update an X.500 directory
    • Used in Windows active Directory, Apple Open Directory, Novell eDirectory, ect.

X.500 Distinguished Names
  • attribute= value pairs
  • Most specific attribute is listed first
    •                 This may be similar to the way you already think





    Wednesday, February 18, 2015

    Common TCP and UDP Ports - CompTIA A+ 220-801: 2.4


    TCP (Transmission Control Protocol)
    • Connection-oriented
    • Reliable delivery
    • Can manage out of order messages or retransmissions
    • Loads and unloads the moving truck
      • Checks for out of order or missing cargo
    UDP- User Datagram Protocol 

    • Connectionless
    • Unreliable
    • No reordering of data or retransmissions
    • Loads and unloads the moving truck
      • Doesn't care about out of order cargo or missing cargo
    Ports in a storm of protocols
    • IPv4 with TCP/UDP
      • Server IP address, server application port number
      • Client IP address, client port number
    • Non-ephemeral ports- permanent port numbers
      • Usually on a server or service
    • Ephemeral ports- temporary port numbers
      • Determined in real-time by the client workstation 
    About port numbers...
    • TCP and UDP ports can be any number between 0 and 65,535
    • Most servers (services) use non-ephemeral port numbers
      • This isn't always the case
      • It's just a number
    • Port numbers are for communication, not security
    • Service port numbers need to be "well known"
    • TCP port numbers aren't the same as UDP port numbers
    A network connection

    TCP ports
    • FTP- File Transfer Protocol- tcp/20 (data), tcp/21 (control)
    • Telnet- tcp/23
    • SMTP- Simple Mail Transfer Protocol- tcp/25
    • DNS- Domain Name Services- tcp/53 (zone transfers)
    • HTTP- Hypertext Transfer Protocol- tcp/80
    • POP3- Post Office Protocol version 3- tcp/110
    • IMAP- Internet Message Access Protocol v4- tcp/143
    • HTTPS- Hypertext Transfer Protocol Secure- tcp/443
    • RDP- Remote Desktop Protocol- tcp/3389
    UDP ports
    • DNS- Domain Name Services
      • udp/5 (queries)

    TCP/IP Addressing - CompTIA A+ 220-801: 2.3


    The ingredients for addressing
    • IP Address, e.g., 192.168.1.165
      • Every device needs a unique IP address
    • Subnet mask, e.g., 255.255.255.0
      • Used by the local workstation to determine what subnet it's on
      • The subnet mask isn't (usually) transmitted across the network
      • You'll ask for the subnet mask all the time
        • What's the subnet mask of this network?
    • Default gateway, e.g., 192.168.1.1
      • The router that allows you to communicate outside of your local subnet
      • The default gateway must be an IP address o the local subnet
    DHCP (Dynamic Host Configuration Protocol)

    • IP address configuration used to be manual
      • IP address, subnet mask, gateway
      • DNS servers, NTP servers ect.
    •  October 1993- The bootstrap protocol
      • BOOTP
    • BOOTP didn't automate everything
      • Some manual configurations ere still required
      • BOOTP also didn't know when an IP address might be available again
    • Dynamic Host Configuration Protocol
      • Initially released in 1997
      • Updated through the years

    An Overview of IPv4 and IPv6 - CompTIA A+ 220-801: 2.3




    IPv4 addresses
    • Internet Protocol version 4
      • OSI Layer 3 address
      • Since one byte is 8 bits, the maximum decimal value for each byte is 255
    IPv6 addresses

    • Internet Protocol v6
      • OSI Layer 3 address
    • Groups of zeros can be abbreviated with a double colon ::
      • Only one of these abbreviations allowed per address
    • Leading zeros are optional
    • Your DNS will become very important
    IPv6 address shortcut
    Public addresses vs. private addresses
    • RFC 1918



    Automatic Private IP Addressing (APIPA)
    • A link-local address
      • No forwarding by routers
    • IETF has reserved 169.254.1.0 through 169.254.254.255
      • Those last 256 addresses are reserve
      • IPv6 reserves fe80::/10 (assigned as fe80::/64)
    • Automatically assigned
      • Uses ARP to confirm the address isn't currently in use
    • Check your IP address 
      • Is it an APIPA address?

    Friday, February 13, 2015

    TCP/IP Subnets - CompTIA A+ 220-801: 2.3


    Why subnet the network?
    The secret behind the IP address
    • The IP adress isn't really a single address
    • An IP address is a combination of a network ID and a host ID
      • The subnet mask determines what part of the IP address is the network and which part is the host
      • The subnet mask is just as important as your IP address!
    Classful subnetting
    • Very specific subnetting architecture
      • Not used since 1993
      • But still referenced in casual conversation
    Subnet classes


    Classless subnetting

    • CIDR (Classless Inter-Domain Routing)
      • Created around 1993
      • Removed the restrictions created by classful subnet masks
      • "Cider" block notation
     CIDR notation
    • 192.168.1.1/24
      • Subnet mask of 255.255.255.0
      • 192.168.1.0 through 192.168.1.255 (254 hosts per subnet)
    • 10.1.0.1/16
      • Subnet mask of 255.255.0.0
      • 10.1.0.0 through 10.1.255.255 (65,534 addresses per subnet)
    • 10.1.0.1/26
      • Subnet mask of 255.255.255.192
      • 10.1.0.0 through 10.1.0.63 (62 addresses per subnet)
    CIDR in action

    Network Cabling - CompTIA A+ 220-801: 2.2


    The importance of cable
    • Fundamental to network communication
      • Incredibly important foundation
    • Usually only get one good opportunity at architecting your cabling infrastructure
      • Make it good!
    • The vast majority of wireless communication uses cables
      • Unless you're an amateur radio operator!
    Fiber communications
    • Transmission by light
      • The visible spectrum
    • No RF signal
      • Very difficult to monitor or tap
    • Signal slow to degrade
      • Transmission over long distances
    • Immune to radio interference
      • There's no RF
     Multimode fiber
    • Short-range communication
      • Up to 2 km
    • Inexpensive light source
      • i.e., LED
    Single-mode fiber
    • Long-range communication
      • Up to 100km without processing
    • Expensive light source
      • Laser beams
    Twisted pair copper cabling
    • Balanced pair operation
      • Two wires with equal and opposite signals
        • Transmit+. Transmit- / Receive+, Receive-
    • The twist is the secret!
      • Keeps a single wire constantly moving away from the interference
      • The opposite signals are compared on the other end
    • Pairs in the same cable have different twist rates

    Shielded and unshielded cable
    • STP (Shielded Twisted Pair)
      • Additional shielding protects against interference
      • Requires the use of an electrical ground
      • Max distance follows the Ethernet standard
     
    • UTP (Unshielded Twisted Pair)
      •  No additional shielding
      • The most common twister pair cabling
      • Max distance follows the Ethernet standard
    No plenum
    Plenum

    Plenum-rated cable
    • Cable jacket
      • Polyvinyl chloride (PVC) or fluorinated ethylene polymer (FEP)
    • Plenum-rated cable may not be flexible
      • May not have the same bend radius
    • Worst-case planning
      • Important concerns for any structure
    • The riser
      • Between-floor connections use riser cable
      • Riser cable fire requirements aren't as strict as plenum cable
    Coaxial cables
    • Two or more forms share a common axis
    • Used in older Ethernet networks
      • 10BASES "Thicknet" RG-8/U (500m), 10BASE2 "Thinnet" RG-58 (185m)
    • Used in television/digital cable
      • Broadband internet
      • RG-56
    • Short distance video
      • RG-59

    Network Connector Types - CompTIA A+ 220-801: 2.1


    ST connector
    • Straight Tip
      • Bayonet connector
    SC connector
    • Subscriber Connector
    • Standard Connector
    • Square Connector
    LC connector
    • Lucent Connector
    • Local Connector
    • Little Connector
    RJ11 connector
    • 6 position, 2 conductor (6P2C)
      • RJ14 uses 6P4C for dual-line use
    • Telephone connection
    RJ45 connector
    • 8 position, 8 conductor (8P8C)
      • Modular connector
    Wiring standards
    RJ11 RJ45 LAN Ethernet/ Network/ Port Cable Tester
    • Cables can foul up a perfectly good plan
      • Test your cables prior to implementation
    • Many connectors look alike
      • Do you have a good cable mapping device?
    • Get a good cable person
      • It's an art
    T568A and T568B termination
    • Pin assignments from EIA/TIA-568-B standard
      • Eight conductor 100-ohm balanced twisted-pair cabling
    • T568A and T568B are different pin assignments for 8P8C connectors
      • Assigns the T568A pin-out to horizontal cabling
    • Many organizations traditionally use 568B
      • Difficult to change in mid-stream
    • You can't terminate one side of the cable with 568A and the other with 568B
      • It won't work.
    BNC connector
    • Bayonet Neill-Concelman
      • Paul Neil (Bell Labs) and Carl Concelman (Amphenol)
    • Coaxial cable connector
      • RG-58 used in 10BASE2
    • Rigid and bulky
      • Would often pull loose or disconnect

    F-connector
    • Cable television
    • RG-6/U cable