Network Administration

How do you convert a decimal value to binary

1. Divide the base value by 2
2. record the result and the remainder (either 1 or 0)
3.keep dividing the result by 2 until the result reaches 0,
4. then write it down from last answer to first answer obtained

What is A-Z in ASCII?

65-90

What is 1-6 in ASCII?

49-54

What is the decimal value of ~ in ASCII?

126

What is the decimal value of ! in ASCII?

33

What is the decimal value of @ in ASCII?

64

What is the decimal value of # in ASCII?

35

What is the decimal value of $ in ASCII

36

What is the decimal value of % in ASCII?

37

What is the decimal value of ^ in ASCII?

94

What are the key components of a computer?

- CPU
- Primary Storage
- Secondary Storage
- Input
- Output
- I/O Controller

What are some end user devices?

- PC/Workstation
- Server
- Printer

What are copper forms in media?

- Unshielded Twisted Pair
- Shielded Twisted Pair
- Coaxial Cable

What are glass forms in media?

- Fibre Optic

What are air forms in media?

- Infrared
- Bluetooth
- WiFi

What are some problems in media and what are their definitions?

- Attenuation: When a signal gets graudually weaker over distance

- Interference: When a signal gets disrupted

What does a repeater do?

Electronic Device that receives a signal and retransmits it at a higher level and or higher power or onto the other side of an obstruction, so that the signal can cover longer distances. (Operates at the physical layer)

What does a hub do?

It lets you connect multiple computers, they are usually used to create a LAN. (Operates at the physical layer)

What does a bridge do?

Connects LANs to a network (operates at the data-link layer)

What does a switch do?

Similar purpose to bridges, but has multiple ports which increases data travel efficiency (operates at the data-link layer)

What does a router do?

Connects computers and transmits data to correct destinations on a network. Forwards data using fastest available path (operates at the network layer)

What does a server do?

It provides a particular service and manages resources

What is necessary to send TCP data?

3-way handshake

What must the medium be?

Copper

What is the 3 way handshake?

It is specific to TCP. The handshake goes SYN, SYN + ACK, ACK.

What is a frame check sequence (FCS)?

4 bytes added at the end of a frame to check for errors

What is the 7th Layer of the OSI Model, and the 4th Layer of the TCP/IP Model?

Application

What is the 6th layer of the OSI Model?

Presentation

What is the 5th layer of the OSI Model?

Session

What is the 4th layer of the OSI Model?

Transport

What is the 3rd layer of the OSI Model?

Network

What is the 2nd layer of the OSI Model?

Data Link

What is the 1st Layer of the OSI Model?

Physical

What is the 3rd Layer of the TCP/IP Model?

Transport Layer

What is the 2nd Layer of the TCP/IP Model?

Internet Layer

What is the 1st Layer of the TCP/IP Model?

Network Access

What range does a class A ipv4 address cover, and what default subnet mask does it have?

Range: 1 - 126
Default Subnet Mask: 255.0.0.0

What range does a class B ipv4 address cover, and what default subnet mask does it have?

Range: 128 - 191
Default Subnet Mask: 255.255.0.0

What range does a class C ipv4 address cover, and what default subnet mask does it have?

Range: 192 - 223
Default Subnet Mask: 255.255.255.0

What is the multicast address range, and what does it do?

Address: 224.0.0.0 - 239.255.255.255
Purpose: Sends data to group of devices at once

What is the IETF address range, and what does it do?

Address: 240.0.0.0 - 255.255.255.254
Purpose: Testing and researching

What is the loopback address range, and what does it do?

Address: 127.0.0.1 - 127.255.255.255
Purpose: Allows devices to communicate to themselves

What is the universal broadcast range, and what does it do?

Address: 255.255.255.255
Purpose: sending messages to all devices in a localnetwork

How do you calculate the network address?

1. Take the binary equivalent of the ip address and subnet mask

2.place them on top of each other and compare them (first bit of both, second etc.)

3. Write out the subnet in binary using the rules below:
- Both bits are 1 = 1
- If not = 0

4.. then convert the binary answer into a decimal number

What is a bus network topology?

all devices run on a single cable

What is a star network topology?

all devices connect to a singular hub

What is a ring network topology?

all devices are arranged in a circle

What is a mesh network topology?

offers two data transmission types: routing and flooding

How do you communicate with other subnets?

Through a router or gateway

How do you communicate via same subnet/LAN

IP address + subnet mask

How do you communicate with other subnets/LANs by host-name

Use a DNS Server

What is necessary for communication with other subnets via ip address?

Default gateway

What is subnet mask's purpose?

Places devices into a heiracy within the network

What is a socket?

the combination of IP addresses and port numbers

How do you calculate subnet masks?

1. Take the number of 1's in the addresses' binary form, that is equal to the number of bits for the network portion.

2. Add 2 onto the CIDR notation example: /24 turns into /26 after taking 2 bits

3. Calculate the new address
Example:
11111111.11111111.11111111.00000000 = 255.255.255.0
After:
11111111.11111111.11111111.11000000 = 255.255.255.192

What are the most common CIDR notations?

- /8 = 255.0.0.0
- /16 = 255.255.0.0
- /24 = 255.255.255.0

How can I determine the host and network portions in CIDR?

Host portion = CIDR Notation

Network Portion = CIDR Notation - 32 = result

What are some benefits of subnetting?

1. Can reduce network congestion
2. Can utilise firewalls to separate subnets which increases network security

How can I calculate supernetting?

1. Take the binary equivalent of both subnet masks

2.place them on top of each other and compare them (first bit of both, second etc.)

3. then identify how many consecutive bits are identical out of the 32 bits

What is the subnet mask requirement for supernetting?

Must have the same subnet mask length

What is the range requirement for supernetting?

Must be in the same IP range

What is the port number for HTTP?

80

What is the port number of FTP?

21

What is the port number of SMTP?

25

What is the port number of DNS?

53

What is the port number of RIP?

520

What is the port number of SNMP?

161

What does ARP do?

Shows the IP address to MAC address mapping table.

What does hostname do?

Displays current devices hostname

What does ipconfig do?

displays IP address as well as other various TCP information.

What does netsh do?

Shows and allows for configuration relating to IPv4/IPv6

What does netstat do?

Shows detailed information for active connections.

What does ping do?

Tests connectivity by sending and receiving packets of data

What does route do?

view and configure the host's local routing table

What does tracert do?

Determine the route a packet takes to a destination

What does pathping do?

Identifies routes taken by packets to destinations, however it additionally looks for packet losses in all routers and subnets in the path

What is DHCP?

A protocol used to automate the assignment of IP Address.

Why use DHCP?

- flexibility for IP address management
- centralises IP configuration

What is scope in DHCP?

The pool of IP addresses to choose from, with each subnet having its own scope

What is exclusion in DHCP?

Prevents DHCP from assigning specific addresses to client devices

What is reservation in DHCP?

Reserves IP addresses for DHCP clients which ensures specific devices will get specific IP addresses

What is necessary for DHCP?

1. Default Gateway
2. DNS Server

What is the DORA process in DHCP?

1. DHCPDISCOVER
2. DHCPOFFER
3. DHCPREQUEST
4. DHCPACKNOWLEDGEMENT

What is a DNS server?

translates the domain name into its associated IP address

What is the structure of DNS?

- Root
- TLD
- Domain

What are the zone types in DNS?

- Primary: read/write copy of dns database, used always
- Secondary: read-only copy of dns database, used for redundancy and sites with slow connections
- Stub: a read-only partial copy of a zone that contains records that are used for locating name servers, used for dynamic conditional forwarding

What are some DNS Zone configuration?

- Master Server: DNS server that hosts copy of domain's zone, default settings forbid their data to be transferred

Dynamic Updates: allows device to update IP address of its A record if a DHCP server has allocated it a different IP address

What are the two types of DNS Queries?

Recursive queries:
- either returns result or error

Iterative queries:
- either returns result or referral to other server

What is the difference between forwarders and conditional forwarders in DNS?

Forwarders
Forwards queries that cannot be resolved by DNS server to:
- isp DNS server
- head office DNS server
- parent domain DNS server

Conditional Forwarders
- forwards queries for a domain to a domains DNS server

What is DNSSEC?

Uses encryption of DNS traffic through public/private key infrastructure

What is split-brain DNS

Design that prevents external parties from getting network details

What is the difference between external and internal DNS?

- Internal DNS: Dynamic, Full copy of zone

- External DNS: Manual, limited number of records

What is SOA in DNS?

start of a zone of authority identifier

What is A in DNS?

Maps domain names to IPv4 addresses

What is AAAA in DNS?

Maps domain names to IPv6 addresses

What is NS in DNS?

indicates name servers that are authoritative for a zone

What is PTR in DNS?

Maps an IP address into a domain name, utilised in reverse lookups

What is CNAME in DNS?

Specifies an Alias

What is MX in DNS?

Specifies a mail exchange server for a DNS domain name

What is SRV in DNS?

Specifies the IP address of servers for specific services