Flashcards in Chapter 7: TCP/IP Basics Deck (57):
The software installed on a system that enables a specific protocol suite to function
Internet Protocol (IP)
Works at the Internet layer, taking data chunks from the Transport layer, adding addressing, and creating the final IP packet.
Internet Control Message Protocol (ICMP) is an error reporting and diagnostic utility and is considered a required part of any IP implementation.
-Command used to query if a host is reachable
-Shows the round trip time (RTT) for the ICMP packet it sends
What is the structure of a simple IP header?
version -> 32 bits (Header Length) -> DSCP -> TTL -> Protocol
Version field of an IP header
Defines the IP address type, i.e. 4 for IPv4 and 6 for IPv6
Header Length field of an IP header
The total size of the IP portion of the packet, which happens to be 32 bits
DSCP field of an IP header
-Differentiated Services Code Point
-Contains data used by bandwidth-sensitive applications
TTL field of an IP packet
-Time To Live
-A counter that decrements by one every time a packet goes through a router.
-Usually 128, can't be higher than 256
Protocol field of an IP packet
Usually either TCP or UDP, and identifies what's encapsulated inside the packet
What percentage of TCP/IP applications use TCP?
TCP's communication rule that requires both the sending and receiving machines to acknowledge the other's presence and readiness to send and receive data.
Used by systems to determine what application needs the received data.
Structure of a simple TCP header
Source p# -> Dest p# -> Sequence # -> ACK
Sequence Number and ACK fields of a TCP header
Enable the sending and receiving computers to keep track of the various pieces of data.
An optional portion of a header that gives both sides detailed info about the state of the connection
A portion of a TCP header that checks it for errors
Application Layer Protocols
Used by TCP/IP applications to move data back and forth between servers and clients
Universal MAC Address
In Windows -> ipconfig
In UNIX/Linux/OSX -> ifconfig
Provide lots of info regarding a system's TCP/IP settings
The part of an IP address that every computer on a network starts with
The part of an IP address that distinguishes each computer from each other
-The IP address of the router that interconnects the LAN to a wider network.
-Usually the lowest host ID in the network
The 32 bit number used to divide the IP address of a host into its network ID and host ID.
-Address Resolution Protocol
-Used to determine the MAC address that corresponds to a particular IP address.
-Internet Assigned Numbers Authority
-Formed to track and disperse IP addresses
-Regional Internet Registry
-Parcels out IP address to large ISPs and major corporations
-Controlled by IANA
-American Registry for Internet Numbers
-The RIR for North America
Taking a single class of IP addresses and chopping it up into multiple smaller groups
Calculating Hosts Formula
2^(# of zeroes in subnet mask) - 2
Calculating Subnets Formula
2^(# of ones added to the subnet mask)
Typing in all of the IP info into each of your clients manually
What should you always do after statically assigning IP info?
Ping the IP address
Dynamic Host Configuration Protocol (DHCP)
Automatically assigns an IP address whenever a computer connects to the network
UDP 67 (servers) and 68 (clients)
A computer configured to use DHCP
When a DHCP client boots up, it automatically sends out a special ________________ over the broadcast address.
DHCP Discover Packet
A server running DHCP server software
When a DHCP client sends a DHCP server a DHCP Discover Request, it responds with a __________.
The range of IP address a DHCP server pulls from.
A DHCP Client sends out a _________ to accept a DHCP Offer.
When a DHCP Client accepts a DHCP offer, the DHCP Server sends out a ____________.
Created by the DHCP server to allow a system requesting DHCP IP info to use that info for a certain amount of time.
Automatic Private IP Addressing (APIPA)
Enables DHCP clients to self-configure an IP address and subnet mask automatically when a DHCP server isn't available.
APIPA cannot issue a __________.
A situation where there probably is a DHCP problem
You can communicate with other computers on your network that came up after the DHCP server went down (since you all have APIPA addresses), but you can't get to the Internet or access computers that retain the DHCP-given address
Command to reestablish a DHCP lease in Windows
Command to reestablish a DHCP lease in UNIX/Linux/OS X
sudo ifconfig eth0 up
Command to release a DHCP release in Windows
Command to release a DHCP release in UNIX/Linux/OS X
sudo ifconfig eth0 down