What are the two most common Transport Layer Protocols?
TCP and UDP
The term for tracking communication between multiple applications on the source and destination host.
Multiplexing.
What is an MTU
Maximum Transmission Unit
What is Segmentation
The process by which the TCP protocol breaks up chunks of data into smaller segments that will fit the MTU of the underlying network layers.
Six Functions of the Transport Layer
- Session Multiplexing
- Identification of Different Applications
- Segmentation
- Flow Control
- Connection-Oriented
- Reliability
Which term is used to describe the application identifier for TCP and UDP applications?
Port Numbers
This function of TCP works to maximize the data transfer rate and minimize the required retransmissions.
Flow Control
What does it mean that TCP is Connection-Oriented?
TCP establishes a session between two IP hosts and maintains the connection during the entire transmission.
What are the three main objectives of TCP Reliability?
- Detection and Retransmission of dropped packets.
- Detection and remediation of duplicate or out-of-order packets.
- Avoidance of congestion in the network.
Which Transport Layer Protocol is Reliable? (As opposed to Best-Effort)
TCP
Which Transport Layer Protocol is Best-Effort only?
UDP
Which Transport Layer Protocol is Connection-Oriented?
TCP
Which Transport Layer Protocol is Connectionless?
UDP
Which Transport Layer Protocol is used for Email, FTP, Web browsing, and downloading?
TCP
Which Transport Layer Protocol is used for Voice streaming, DHCP, and TFTP?
UDP
What are the three steps in a Three-Way-Handshake?
SYN, SYN-ACK, ACK
At what layer of the OSI model does TCP operate?
Layer 4
Purpose and Size of the Source Port on a TCP Header?
Purpose: Contains the Calling Port Number
Size: 16 bits
Purpose and Size of the Destination Port on a TCP Header?
Purpose: Contains the Called Port Number
Size: 16 Bits
Purpose and Size of the Sequence Number on a TCP Header?
Purpose: Used for reliability and congestion avoidance
Size: 32 Bits
Purpose and Size of the Acknowledgment Number on a TCP Header?
Purpose: Used for reliability and congestion avoidance
Size 32 Bits
Purpose and Size of the “Header Length” field on a TCP Header?
Purpose: Size of the TCP Header
Size: 4 bits
Purpose and Size of the Reserved field on a TCP Header?
Purpose: Reserved for future use.
Size: 3 bits
Purpose and Size of the Flags field on a TCP Header?
Purpose: These are control bits
Size: 9 bits.
List the nine different Flags in the Flag field of a TCP Header.
- Nonce Sum (NS)
- Congestion Windows Reduced (CWR)
- Explicit Congestion Notification Echo (ECE)
- Urgent (URG)
- Acknowledgment (ACK)
- Push (PSH)
- Reset (RST)
- Synchronize (SYN)
- Finish (FIN)
Purpose and Size of the “Window Size” field on a TCP Header?
Purpose: Allows the receiving computer to advertise how much data it can receive before having to drop packets. Used for Flow Control.
Size: 16 bits.
Purpose and Size of the Checksum field on a TCP Header?
Purpose: Error Checking
Size: 16 bits
Purpose and Size of the “Urgent Pointer” field on a TCP Header?
Purpose: If the URG flag is set, this field is an offset from the sequence number indicating the last urgent data byte.
Size: 16 bits
what determines the size of the Options field on a TCP Header?
The data offset field.
What is the purpose of the Data field in a TCP Header
Contains the Upper-Layer protocol data.
List the 5 fields in a UDP segment.
- Source Port
- Destination Port
- Length
- Checksum
- Data
Port # and Protocol used for FTP
Port 21, TCP
Port # and Protocol used for SSH
Port 22, TCP
Port # and Protocol used for Telnet
Port 23, TCP
Port # and Protocol used for HTTP
Port 80, TCP
Port # and Protocol used for HTTPS
Port 443, TCP
Port # and Protocol used for DNS
Port 53, Both TCP and UDP
Port # and Protocol used for TFTP
Port 69, UDP
Port # and Protocol used for SNMP
Port 161, UDP
Define HTTP
Hyper Text Transfer Protocol
List the 5 steps in an HTTP Request-Response Cycle
- Client Sends an HTTP request to the server.
- Server receives the request.
- Server Processes the request.
- Server returns an HTTP response.
- Client receives the response. (eg., web page content)
Define DNS
Domain Name System
This command queries DNS to resolve the domain name into IP address.
nslookup
Define DHCP
Dynamic Host Configuration Protocol
Three basic DHCP IPv4 allocation mechanisms
- Dynamic Allocation.
- Automatic Allocation.
- Static Allocation.
Four Steps in Dynamically allocating an IPv4 address using DHCP
- Discover.
- Offer.
- Request.
- Acknowledge.
Command to configure a Router as a DHCP Client.
Router(config-if)# ip address dhcp
Command to verify that a router interface has aquired an IPv4 address through DHCP.
Router# show ip interface brief
Command to configure a router for DHCP Relay
Router(config-if)# ip helper-address 10.0.0.1
Command to enter the DHCP pool configuration mode.
Router(config)# ip dhcp pool (Name you’re assigning to the pool).
Command that displays a list of all IPv4 address-to-MAC bindings
Router# show ip dhcp binding
Command to verify information about the configured DHCP address pools.
Router# show ip dhcp pool
Command to verify which services are running on a router.
Router# show control-plane host open-ports
Command to disable the HTTP service on a router
Router(config)# no ip http server
