Q1: Write a short note on any four categories of network security? (0.5 pts) Q2:

Question

Q1: Write a short note on any four categories of network security? (0.5 pts)

Q2: Among the two methods DHCP is the one to distribute IP addresses more efficiently. Explain   it in brief how distribution is done by DHCP?        (0.5 pts)

Q3: What are the advantages of switched Ethernet over hub- or bus-based Ethernet?         (1 pts)

Q4: Explain the major differences between TCP and UDP   (1pts)

Q5:

a) Who owns Internet backbones? (0.5 pts)

b) What is the major difference in implementation between a LAN and a MAN or WAN? (1pts)

c) What is the major advantage of layering in the network model? (0.5 pts)

Explanation / Answer

Categories network security

t1) Wired Equivalent Privacy (WEP)

2) MAC Adress

3) Firewall

4) 802.1X authentication

5)Physical Security

Wired Equivalent Privacy (WEP):

WEP is an older network security method that is still available to support older devices, but it is no longer recommended.
When you enable WEP, you set up a network security key. This key encrypts the information that one computer sends to another computer across your network. However, WEP security is relatively easy to crack

MAC Adress:

A Media Access Control address is a unique identifier assigned to network interfaces for communications on the physical network segment. Can be described as Ethernet hardware address (EHA), hardware address or physical address. It is assigned by the manufacturer of a network interface card (NIC) and are stored in its hardware, the card's read-only memory, or some other firmware mechanism.

The advantage to MAC filtering is that there is no attachment cost to devices that connect to the network. The policy is set on a router or switch, and the equipment attached either is permitted or it is not. The person attaching the equipment has nothing to do.

The disadvantage to MAC filtering is that it is easy to spoof due to the broadcast nature of LAN and WLAN, an advisory can sit on the wire and just listen to traffic to and from permitted MAC addresses. Then, the advisory can change his MAC address to a permitted one, and in most cases obtain access to the network.

Firewall
The main objective of firewall is to control the incoming and outgoing network traffic by analyzing the data packets and determining whether it should be allowed through or not, based on a predetermined set of rules. It can be hardware or software.
The advantage of a firewall is that the user can monitor incoming and outgoing security alerts and the firewall company will record and track down an intrusion attempt depending on the severity. Some firewalls can detect viruses, worms, Trojan horses, or data collectors.
802.1X authentication

802.1X uses an authentication server to validate users and provide network access.802.1X authentication can help enhance security for 802.11 wireless networks and wired Ethernet networks. On wireless networks, 802.1X can work with WEP or WPA keys. This type of authentication is typically used when connecting to a workplace network.

Physical Security
Something that is physical i.e someone breaking into a system.

E.g. a watchman,or a bench

Q4) differences between TCP and UDP

The fields of TCP are

1.Sequence Number, 2. AcK number, 3. Data offset, 4. Reserved, 5. Control bit, 6. Window, 7. Urgent Pointer 8. Options, 9. Padding, 10. Check Sum, 11. Source port, 12. Destination port

The fields of UDP are

1. Length, 2. Source port, 3. Destination port, 4. Check Sum

Q5:

a) Who owns Internet backbones?

The Internet backbone is a conglomeration of multiple, redundant networks owned by numerous companies. It is typically a fiber optic trunk line. The trunk line consists of many fiber optic cables bundled together to increase the capacity. The backbone is able to reroute traffic in case of a failure.The data speeds of backbone lines have changed with the times. slowest data rate is of 45 Mbit/s. However the changing technologies allowed for 41 percent of backbones to have data rates of 2,488 Mbit/s or faster by the mid 2000s. Fiber-optic cables are the medium of choice for Internet backbone providers for many reasons. Fiber-optics allow for fast data speeds and large bandwidth; they suffer relatively littleattenuation, allowing them to cover long distances with few repeaters; they are also immune to crosstalk and other forms of electromagnetic interference which plague electrical transmission.

TCP UDP TCP is a connection-oriented protocol. TCP is a connectionless protocol. The applications of TCP are high reliability, and transmission time is relatively less critical. The applications of UDP are need fast, efficient transmission, such as games. UDP's stateless nature is also useful for servers that answer small queries from huge numbers of clients. Other protocols like HTTP, HTTPs, FTP, SMTP, Telnet use TCP Other protocols like DNS, DHCP, TFTP, SNMP, RIP, VOIP use UDP Trasfer speed for TCP is slower than UDP UDP is faster because there is no error-checking for packets. TCP header size is 20 bytes TCP header size is 20 bytes

The fields of TCP are

1.Sequence Number, 2. AcK number, 3. Data offset, 4. Reserved, 5. Control bit, 6. Window, 7. Urgent Pointer 8. Options, 9. Padding, 10. Check Sum, 11. Source port, 12. Destination port

The fields of UDP are

1. Length, 2. Source port, 3. Destination port, 4. Check Sum

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