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

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?

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