TCP/IP Protocol Fundamentals Flashcards
What is the purpose of NAT/PAT?
- Translates an IPv4 address from the private ranges into an address that is routable across the internet.
- Allows devices on the internal network to access services located on the internet
What are the two major components of an IPv4 address?
- Network: identifies the network segment/subnet on which a particular device is connected
- Host: identifies the specific device to which the whole IP address is assigned
What is the Class A IPv4 private address range?
10.x.x.x /8
What is the purpose of a network mask in IPv4 and how is it represented?
- Represented in the same four octet format as the IP address it is attached to
- Identifies which portions of the IP address are network address and host address
- On bits (1s) identify the network portion of an IP while off bits (0s) identify the host portion.
Describe Layer 4 of the TCP/IP protocol stack and its function
- Transport layer
- Defines UDP and TCP port numbers used by specific applications, services, and protocols
- Port numbers define, on both transmitting and receiving ends, what service is trying to be accessed (HTTPS, DNS, DHCP etc)
What is the Class C IPv4 private address range?
192.168.x.x /16
How can you locate the network information on a Windows device, including MAC address and IP address configuration? On Linux? On Mac?
- Windows: from command prompt issue “ipconfig /all” command
- Linux and Mac: from terminal issue “ifconfig” command
How are IPv4 address classes identified?
- Each primary class has an associated default subnet mask length and range of values within the first octet
- Class A: 1 - 127.x.x.x /8 (255.0.0.0)
- Class B: 128-191.x.x.x /16 (255.255.0.0)
- Class C: 192-223.x.x.x /24 (255.255.255.0)
What are IPv4 private addresses?
- IPv4 address ranges reserved for private use within an organization
- Can be used for routing within a private organization’s intranetwork, however not routable across the internet
Describe Layer 1 of the TCP/IP protocol stack and its function
- Physical layer
- Deals with encoding, hardware specifications, voltage etc needed to translate digital information into physical currents sent across desired medium
How is every device assigned a unique MAC address?
- IEEE assigns the first six characters of a MAC address to the vendor making and distributing the network card. This means the manufacturer of that card can be identified by the first six characters of the MAC.
- The manufacturer is responsible for creating a unique MAC address with the final six characters
What is the advantage of computer networking?
- Allows resources to be shared. Multiple devices within an organization can share print services, file storage, application access etc without having to set up individually per device.
- Improves ease of collaboration
What is the Class B IPv4 private address range?
172.16-31.x.x /12
Describe Layer 2 of the TCP/IP protocol stack and its function
- Data Link layer
- Handles physical addressing of network devices and how traffic is forwarded along a network segment
- Physical addresses burned in and unique to a specific device
What is ARP and how does it work?
- Address Resolution Protocol (ARP)
- MAC address needed to communicate with devices on the local network segment
- ARP discovers and stores MAC addresses, mapping them to particular network addresses
- If the IP address of a device running a particular service is known but the MAC address associated with that IP is not the initiating device sends out an ARP request.
- The ARP request is a broadcast that goes out to every device on the segment and will hopefully be received the device with the matching IP.
- The device with the target IP responds with its MAC address which is stored on the initiators ARP cache for later
How do you clear the ARP cache on a Windows PC?
In the command prompt use the “arp -d” command
Describe the structure of an IPv4 address.
- Divided into four octets: A.B.C.D
- Each octet can represent a number between 0 and 255
- Each octet is a decimal representation of an 8-bit binary value (0 = 00000000 and 255 = 11111111 and every number in between is represented by a different combination of these bits turned on or off)
How do you check the ARP cache on a Windows PC?
In the command prompt use the “arp -a” command
What is the function of the Application Layer in the TCP/IP protocol stack?
Defines the service to be used, such as HTTP, DNS, SMTP etc
What is an Ethernet Address? What might it also be referred to as?
- Can be referred to as physical address, Media Access Control (MAC) address, hardware address, layer 2 address, Burned In Address (BIA)
- A unique address permanently tied to a unique network card installed in a device
- 12 hexadecimal characters long
- Each hex character represents 4 bits therefore each address represents 48-bits
Describe Layer 3 of the TCP/IP protocol stack and its function
- Network layer
- Handles logical addressing of network devices, most commonly IP in today’s networks
- Identifies the network a device is a part of so that traffic for that device can be routed accordingly
Why are MAC addresses unique?
- MAC addresses identify a unique device on the network segment. Duplicate MAC addresses can cause communication issues for matching devices on the segment.
- A unique MAC address is useful for identifying a specific device for accounting and auditing purposes
How many primary IPv4 address classes are there and what are they? Are there others?
- 3 primary classes
- Class A, Class B and Class C
- There are others used for specific purposes such as testing and research
