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IP Fundamentals
Question | Answer |
---|---|
Good Acronym for 7 Layers of OSI Model | All Programmers Seem To Need Data Processing |
What are the 7 layers of the OSI Model | Application Presentation Session Transport Network Data Link Physical |
1 (Physical) Example Protocols | Ethernet, USB, Bluetooth |
2 (Data Link) Example Protocols | Ethernet, Frame Relay, PPP |
3 (Network) Example Protocols | IPV4, IPv6, IPX Logical Addressing, Routing, Path Determination |
4 (Transport) Example Protocols | TCP, UDP, SCTP |
5 (Session) Example Protocols | NetBIOS, SAP |
6 (Presentation) Example Protocols | MIME, TLS, SSL Encryption & Compression |
7 (Application) Example Protocols | FTP, HTTP, Telnet |
How does the OSI model map over to the TCP/IP model? | Application = Application, Presentation, Session Transport = Transport Internet = Network Link = Data Link & Physical |
Benefits of TCP and UDP? | TCP (Session-oriented) = Flow Control & Error Correction UDP (Session-less) = Speed |
Describe the UDP Header | -Source Port -Destination Port -Length -UDP Checksum |
UDP Header Length | 8 bytes |
DNS Function & Protocols | Domain Name System -Uses UDP for simple requests/replies to resolve hostnames -Uses TCP for larger messages and zone transfers |
DHCP Function & Protocols | Dynamic Host Configuration Protocol -Uses UDP to assign dynamic IP addresses to hosts |
Describe TCP Header | -Source Port -Destination Port -Sequence Number -Offset -Reserved (=0) -Flags -Window -Checksum -Urgent Pointer -Options -Padding |
TCP Header Length | 4 bytes (32 bits) |
BGP Function & Protocols | Border Gateway Protocol -Core routing protocol of the Internet -Runs entirely over TCP (maintains table of IP networks) |
Port 20, 21 | 20 = FTP Data 21 = FTP Control |
Port 23 | Telnet |
Port 53 | DNS |
Port 80 | HTTP |
Port 143 | IMAP |
Port 161 | SNMP (Simple Network Management Protocol) |
Describe IPv4 Packet Structure | -Version -Header Length -ToS/DiffServ -Total Length -Identifier -Flags -Fragment Offset -TTL -Protocol -Header Checksum -Source Address -Destination Address -Options -Padding |
TCP Flags (6) | 1 = Urgent (URG) 2 = Acknowledgemnt (ACK) 3 = Push (PSH) 4 = Reset Connection (RST) 5 = Synchronous (SYN) 6 = Finish (FIN) |
IPv4 Address Length | 32 bits (4 octets w/ dec = 0-255 range) |
Class A | N.H.H.H -Big Networks -First bit always 0 (1-126 Range) |
Class B | N.N.H.H -Medium Networks -First two bits always 10 (128-191 Range) |
Class C | N.N.N.H -Small Networks -First three bits always 110 (192-223 Range) |
224.0.0.0-239.255.255.255 | Class D (reserved for Multicast) |
240.0.0.0-254.255.255.254 | Class E (reserved) |
10.0.0.0-10.255.255.255 | 1 Private Class A Network |
172.16.0.0-172.31.255.255 | 16 Private Class B Networks |
192.168.0.0-192.168.255.255 | 256 Private Class C Networks |
What OSI Layer interfaces directly with applications running on devices? | 7 - Application |
What OSI Layer converts code and reformats data? | 6 - Presentation |
What OSI Layer coordinates interaction between end-to-end application processes? | 5 - Session |
What OSI Layer provides end-to-end data integrity and quality of service? | 4 - Transport |
What OSI Layer switches and routes data to the appropriate network device? | 3 - Network |
What OSI Layer transfers units of data to the other end of the physical link? | 2 - Data Link |
What OSI Layer transmits and receives on the network medium? | 1 - Physical |
IPv4 Minimum Length | 20 Bytes (20 octets) |
Special Use IP Address Space | 0.0.0.0/8 "This" Network 127.0.0.0/8 Loopback 169.254.0.0/16 Link Local 192.0.2.0/24 Test-Net |
Class A First Octet Range | 1-126 |
Class B First Octet Range | 128-191 |
Class C First Octet Range | 192-223 |
Class D First Octet Range | 224-239 |
Class E First Octet Range | 240-254 |