Download 1. Application layer, Transport layer, Internet layer, Link layer 2

1.
Application layer, Transport layer, Internet layer, Link layer
2.
Application layer: DHCP, HTTP, BGP, SMTP, POP
Transport layer: TCP, UDP,
Internet layer: IP, ICMP, IPSec
Link layer:
ARP, PPP
3. Switches operate at Layer 2 of the OSI model and switch frames
based on the MAC addresses. Switches only forward frames within the
same broadcast domain. Routers operate at the Layer 3 of the OSI model
and route packets based on the network IDs (IP addresses). Routers
route packets to different network domains. If a destination is not known to
a switch, it broadcasts the frame, whereas a router may drop a packet if
the destination is not known (or send on a default route, depending
uptown scenario/configuration).
4. A packet is a protocol delivery unit (PDU) that is exchanged between
hosts at Layer 3 of the OSI model. In TCP/IP, IP packets consist of a
header and payload and are routed based on the source/destination IP
addresses contained in the header, amongst other things. A frame is a
PDU at the Layer 2 of the OSI model. A packet is encapsulated in one of
more frames (depending on the size of the packet and maximum
transmission unit of the frame) e.g. in Ethernet frames.
5. Connection-oriented protocols require that a logical connection be
established between two device before transferring data. Connectionless
protocols do not establish a connection between devices before
exchanging data, the sender starts sending as soon as it wants to, without
considering if the receiver is able to receive data, can accommodate a
certain data rate, etc. TCP is a connection-oriented protocol, whereas
UDP Is a connectionless protocol.
6. Unicast: When information is sent from one point to another e.g. a
packet is sent from a single source to a specified destination.
Multicast: Communication in which information is sent from one or
more points to a set of other points e.g. as in IP multicast using UDP.
Broadcast: Communication in which a price of information is sent
from one point to all other points, e.g. in a LAN
7. RIP and BGP are routing protocols, where as Store-and-Forward is
the one of the methods used in switching e.g. Switches can store an
incoming frame and then send it to its destination later.
8. Sliding window protocols are used to enforce reliable in-order
delivery of packets. Each packet is assigned a unique consecutive
sequence number and the receiver uses the numbers to place received
packets in the correct order. Duplicate packets are discarded and any
missed packets are identified using this sequencing. To limit the
sequence of numbers from growing unreasonably large, limits are placed
on the number of packets than can be transmitted or received at any given
time before requiring an acknowledgement. Thus unlimited number of
messages can be exchanged using fixed-size sequence numbers.
9. Maximum Transmission Unit, the size of the largest protocol data unit
at a layer in the network stack. Ethernet MTU is 1500 octets
10. Distributed Denial of Service Attack, in which the intention is to make
a network host - and hence any services it provides - unavailable to its
users.
11. ARP
12. DNS
13. traceroute (tracert on Windows)
14. HTTP 80
FTP
21
SSH
22
TELNET 23
SMTP 25
15. By using the 'ping' command