Networks

Test your networking knowledge

A three-part networking exercise covering communications and protocols, IP addressing and a network diagram, followed by the complete set of answers.

· 5 min read · level: beginner

Part 1. Communications and protocols

Part 2. IP addressing

Part 3. Network diagram

Part 1. Communications and protocols

1. Which command is used to test the connectivity of a host on the network, and which protocol is associated with it?

2. What is an FTP client? Give an example of use.

3. When you access a page from a web browser, which protocol is used and which communication port is associated with it?

4. You would like to secure communication toward web servers; how would you go about it? Which port and which protocols are involved?

5. You do not want to accept the TELNET protocol on a network; which actions are required?

6. What is the name of the protocol suite most widely used in computer communications? Name at least 7 protocols belonging to it.

7. What are IP addresses and port numbers used for?

8. What are the two significant parts of an IP address and what do they represent? How do you tell them apart?

9. On how many bits are IPv4 and IPv6 addresses encoded, and in what form are they represented?

10. What is a MAC address? On how many bits is it encoded and in what form is it represented?

Part 2. IP addressing

1. For the IPv4 address 172.16.16.61 /16. Find:

  • The network address 172.16.0.0
  • The subnet mask 255.255.0.0
  • The broadcast address 172.16.255.255
  • The range of usable IP addresses 172.16.0.1 -> 172.16.255.254

2. For the IPv4 address 10.0.1.111 /8. Find:

  • The network address 10.0.0.0
  • The subnet mask 255.0.0.0
  • The broadcast address 10.255.255.255
  • The range of usable IP addresses 10.0.0.1 -> 10.255.255.254

3. For a network of 177 hosts. Determine:

  • A network address 192.168.1.0
  • A subnet mask 255.255.255.0 = 2^8-2 = 254 hosts
  • A broadcast address 192.168.1.255
  • A range of usable IP addresses 192.168.1.1 -> 192.168.1.254

Bonus: Give the class associated with each of these 3 networks.

Part 3. Network diagram

Produce a diagram from the following elements (using a tool such as Cisco Packet Tracer):

  • A router with 3 GigabitEthernet interfaces
  • A WAN connection with the public IP 200.212.36.9
  • Two LAN networks: 172.16.0.0/16 and 10.0.0.0/8, interconnected by the router.
  • Three separate servers: an FTP server, a web server and a database server, on the 172.16.0.0 /16 network.
  • A Wi-Fi access point on the 10.0.0.0 /8 network with at least one computer connected.

#réseaux

Answers:

1. The command used for the connectivity test is ping and the protocol used is ICMP

2. An FTP client is a program that lets you connect to an FTP server in order to exchange files with it. Filezilla, winscp

3. When accessing a web page, the protocol used is http on communication port 80.

4. To secure the http protocol, the SSL or TLS protocol must be added on top of http, which gives https on port 443 by default.

5. Port 23 must be blocked on the firewall or firewalls.

6. TCP/IP – DNS DHCP TCP IP UDP SSH HTTP IMAP POP FTP TELNET ICMP SMTP IMAP OSPF ARP

7. The IP address identifies a computer or any other device on the network, whereas the port number indicates the application (the service) the data is intended for.

8. The network part and the host part. The subnet mask makes it possible to tell these two parts apart. Network part 192.168.0.11 255.255.255.0 Host part

9. IPv4 = 32 bits decimal, IPv6 = 128 bits hexadecimal.

10. The MAC address (for Media Access Control) is the physical address of a network device (NIC, for Network Interface Card). Each MAC address is supposed to be unique worldwide. It can therefore be considered a kind of license plate for electronic devices. The MAC address can be modified in certain cases. It is encoded on 48 bits and displayed in hexadecimal form.

Part 2:

11. 172.16.16.61 /16 = Class B

@R 172.16.0.0

Subnet mask: 255.255.0.0

@Br: 172.16.255.255

172.16.0.1 to

172.16.255.254

2. 10.0.1.111 /8 = Class A

@R 10.0.0.0

Subnet mask = 255.0.0.0

@Br: 10.255.255.255

10.0.0.1 to

10.255.255.254

3. 192.168.0.0 /24 = Class C

@R 192.168.0.255

Subnet mask = 255.255.255.0 /24 = 254 possible hosts

192.168.0.1 to

192.168.0.254

Part 3:

Router configuration:

en

conf t

int gig 0/0

ip address 200.212.36.9 255.255.255.0

no shutdown

int gig 0/1

ip address 172.16.0.1 255.255.0.0

no shutdown

int gig 0/2

ip address 10.0.0.1 255.0.0.0

no shutdown

ip dhcp pool 172.16

network 172.16.0.0 255.255.0.0

default-router 172.16.0.1

dns-server 1.1.1.1

ip dhcp pool 10

network 10.0.0.0 255.0.0.0

default-router 10.0.0.1

dns-server 1.1.1.1