Volume 2 - Chapter 5: Introduction to TCP/IP Transport and Applications Flashcards
TCP is defined in which RFC?
RFC 9293.
A socket is comprised of what 3 components
An IP address
A transport protocol
A port number
What organization is responsible for subdividing port number ranges?
The Internet Assigned Numbers Authority (IANA)
What are the 3 main ranges of ports defined by the IANA?
- Well Known (System) Ports
- User (Registered) Ports
- Ephemeral (Dynamic/Private) Ports
What is the range of Well Known (System) Ports?
0 to 1023.
What is the range of User (Registered) Ports?
1024 to 49151.
What is the range of Ephemeral (Dynamic, Private) Ports?
49152 to 65535.
Describe the difference between Well Known and User Ports.
Well Known ports have a stricter review process for assigning ports in comparison to user ports.
Describe the difference between User ports and Ephemeral ports.
Ephemeral ports are dynamically assigned an intended for temporary use for client applications.
What are the ports and transport protocol(s) used for FTP data and FTP control?
FTP Data: Port 20/TCP
FTP Control: Port 21/TCP
What is the port and transport protocol used by SSH?
Port 22/TCP.
What is the port and transport protocol used by Telnet?
Port 23/TCP.
What is the port and transport protocol used by SMTP?
Port 25/TCP
What is the port and transport protocol used by DHCP servers?
Port 67/UDP
What is the port and transport protocol used by DHCP clients?
Port 68/UDP
What is the port and transport protocol used by TFTP?
Port 69/UDP
What is the port and transport protocol used by POP3?
Port 110/TCP
What is the port and transport protocol used by SNMP?
Port 161/UDP
What is the port and transport protocol used by Syslog?
Port 514/UDP
Describe the TCP 3-way handshake.
- Client: SYN to Server
- Server: SYN, ACK to Client
- Client: ACK to Server
What is the size of the flag field in the layer 4 header?
2 bits
Describe the function of a connection-oriented protocol.
A protocol that requires a prestablished connection before the data transfer begins.
Describe the function of a connectionless protocol.
A protocol that does not require a prestablished connection before the data transfer begins.
Describe the function of sequences and acknowledgements in regards to TCP.
The sequence number identifies which part of the data is being sent.
The acknowlege is used confirm on the server which parts have been received, and if need re-transmit any lost messages.
A web server receives the following sequences from a connected client:
* 1000 bytes of data; sequence 1000
* 1000 bytes of data; sequence 2000
* 1000 bytes of data; sequence 4000
How will the web server respond to the client?
By sending an acknowledgement of 3000 to the client; indicating that it did not receive sequence 3000.
A web server receives the following sequences from a connected client:
* 500 bytes of data; sequence 500
* 500 bytes of data; sequence 1000
* 500 bytes of data; sequence 1500
How will the web server respond to the client?
By sending an acknowledgement of 2000 to the client; indicating that it received all sequences and is ready to receive the sequences (byte 2000).
A web client has sent the following sequences to a web server:
* 1000 bytes of data; sequence 1000
* 1000 bytes of data; sequence 2000
* 1000 bytes of data; sequence 3000
* 1000 bytes of data; sequence 4000
* 1000 bytes of data; sequence 5000
The web server responds with an acknowledgement of 3000. What will the web client do?
The client will resent sequence 3000 because it has been lost in transit and the web server has not received it.
Describe the purpose of TCP Flow Control using windowing.
As data is consistently being sent and received between the client and server, the server can grant a larger window size to allow more data to be sent before an acknowlegement is required.
What are the sizes of the TCP and UDP headers respectively?
TCP: 20 bytes
UDP: 8 bytes
What does URI stand for?
Uniform Resource Indicator.
What are the 3 components of a URI?
The scheme, the authority, and the path.
What part of the URI indicates the specific page being requested?
The path, for example:
/mainpage
What part of the URI indicates the specific web server that is being connected to?
The authority, for example:
www.mywebsite.com
What part of the URI indicates the specific web protocol that is being used to connect?
The scheme, for example:
https:// or http://
A DNS server that does not have a result for a specific hostname and needs to request additional information for another DNS server is referred to as?
A recursive DNS server.
The HTTP application layer protocol is defined in what RFC?
RFC 7230.
An HTTP return code of 200 means what?
Ok.
An HTTP return code of 404 means what?
Not found.
An HTTP return code of 403 means what?
Forbidden.
What key field in the Ethernet header identifies what type of IP packet it contains?
The type field.
What key field in the IP header identifies what type of transport protocol is being used?
The protocol field.
What key field in the TCP/UDP header identifies what type of application port the data will be received on?
The destination port.
What decimal value represents TCP in the IP header?
6.
What decimal value represents UDP in the IP header?
17.
What hexadecimal value represents IPv4 in the Ethernet header?
0800
Which version of HTTP standardized the following?:
* Port 80 as the application port
* TCP as the transport protocol
* GET response/request messages
HTTP 1.0 and 1.1
What version of HTTP introduced the following?:
* The option for secure communications using TLS
* Port 443 as the application port for secure communications
HTTP/2
What version of HTTP introduced the following?:
* Using QUIC as the transport protocol which is based on UDP
HTTP/3