TCP/UDP

Question 1

What are the three categories of port numbers?

Answer 1

Well known : 1-1023
Registered : 1024-49151
Dynamic : 49152-65535

Question 2

What is a socket?

Answer 2

Combination of an IP address and port

Ex 192.168.1.100:23

Question 3

What is TCP?

Answer 3

Transmission Control Protocol

Question 4

Describe TCP

Answer 4

Connection oriented. Hosts establish connection using three way handshake
Segmentation - breaks data too big for a frame into frame sized segments.
Segments are sequenced allowing reassembly in correct order with checksums to ensure integrity
Flow control - uses transmission window sizes and messaging to control transmission rate

Question 5

Explain the three way handshake

Answer 5

SYN
Client rings the server

SYN/ACK
Server says hello (ACK)
Server identifiers itself (SYN)

ACK
Client confirms connection

_________________________
Host A sends a TCP SYNchronize packet to Host B

Host B receives A’s SYN

Host B sends a SYNchronize-ACKnowledgement

Host A receives B’s SYN-ACK

Host A sends ACKnowledge

Host B receives ACK.
TCP socket connection is ESTABLISHED

Question 6

Explain UDP (user datagram protocol)

Answer 6

Connectionless- hosts unknown to each other
No segmentation- more efficient for data that fits into one frame
No sequencing and checksums
No integrity
No guarantee of correct sequence or arrival

Question 7

What is the DORA process in DHCP?

Answer 7

Discover
Offer
Request
Acknowledgement
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_
ASWINI DEY
 May 28th, 2013

HCP (D)Discover
DHCP (O)ffer
DHCP (R)equest
DHCP (A)ck

Step 1:

Your computer sends a “Discovery” request, asking for its IP information from any listening DHCP servers.

Step 2:

Any listening DHCP servers will “Offer” their configuration information to your workstation.

Step 3:

You workstation chooses the best lease then “Requests” that lease from the corresponding DHCP server.

Step 4:

The DHCP server you requested the IP configuration information from then “Acknowledges” your request and leases you the IP configuration information.

Question 8

What is DHCP?

Answer 8

Dynamic Host Configuration Protocol
A client/server protocol that automatically assigns an IP address to it’s IP host and other related config info such as subnet mask, default gateway, etc.

Question 9

What are the four layers of the DoD model?

Answer 9

Process/Application
Host-to-Host
Internet
Network Access

Question 10

What are some of the protocols that take place in the process/application layer of the DoD model? (AKA Application/Presentation/Session in OSI)

Answer 10

Telnet, FTP, LPD, SNMP, TFTP, SMTP, NFS, X Window, SSH, DHCP

TFTP - Trivial File Transfer Protocol
SMTP - Simple Mail Transfer Protocol
SNMP - Simple Network Management Protocol

Question 11

What are some of the protocols that take place in the Host-to-Host layer of the DoD model? (AKA Transport layer in OSI)

Answer 11

TCP/UDP

Question 12

What are some of the protocols that take place in the Internet layer of the DoD model? (AKA Network layer in OSI)

Answer 12

ICMP, ARP, RARP, IP

Question 13

What are some of the protocols that take place in the Network Access layer of the DoD model? (AKA Data Link/Physical layer in OSI)

Answer 13

Ethernet, Fast ethernet, Gigabit ethernet, wireless/802.11