COMP609 Final Exam Revision Notes

COMP609 Final Exam Revision

Assessment Instructions

• Individual assessment: No discussion or collaboration is allowed.

• No component of the assessment may be shared.

• Do not start typing/writing until instructed. Candidates must not write/type during reading time.

• Turn on the computer and log into Canvas during reading time.

• Closed Book Examination (online canvas-based exam) via Canvas (Assignments-> Final Exam 2024 S1).

• One submission attempt.

• Ensure frequent saving and do not leave the assessment before clicking Save and Submit.

• Answer ALL the questions.

• No dictionaries are allowed.

Exam Summary

The exam is divided into four sections:

• Multichoice Questions: 20 marks, 20 minutes.

• True/False Questions: 20 marks, 20 minutes.

• Fill-in the blanks Questions: 20 marks, 20 minutes.

• Short/Long answer Questions: 40 marks, 60 minutes.

• Total: 100 marks, 120 minutes.

Fiber vs Copper

Optical fiber is primarily used as backbone cabling for high-traffic, point-to-point connections between data distribution facilities and for the interconnection of buildings in multi-building campuses.

Topics Covered

1. DNS: Query types (recursive and iterative), hostname, namespace, etc.

2. DHCP: Lease acquisition process, lease renewal process.

3. TCP three-way handshake.

4. Subnet mask: Class A, B, and C in both binary & decimal.

5. Network Security: Virus, Trojan, spyware, etc. Network attacks – DDOS, Ip-spoofing, etc.

6. RAID: RAID 0, 1, 5

7. VPN: Protocol, Transport & tunnel, IPSec

8. Commands: ipconfig /all, ipconfig /flushdns, etc.

9. Access list: standard, extended

Network Trends - Cloud Computing

Four types of Clouds:

• Public Clouds

  • Available to the general public through a pay-per-use model or for free.

• Private Clouds

  • Intended for a specific organization or entity such as the government.

• Hybrid Clouds

  • Made up of two or more Cloud types – for example, part custom and part public.

  • Each part remains a distinctive object but both are connected using the same architecture.

• Custom Clouds

  • Built to meet the needs of a specific industry, such as healthcare or media.

  • Can be private or public.

IPv4 Addressing

• An IPv4 address is a 32-bit number divided into four 8-bit numbers (octets).

• These octets range in number from zero to 255.

• Example: 192.168.1.20

• The biggest IP address possible is 255.255.255.255.

• In binary, this IP address looks like this: 11111111.11111111.11111111.11111111

• Binary to Decimal Conversion Example:

  • Binary: 10000001

  • Decimal: 128 + 1 = 129

IPv4 Address Structure - Network and Host Portions

• An IPv4 address is a 32-bit hierarchical address that is made up of a network portion and a host portion.

• To determine the network vs. host portion, examine the 32-bit stream.

• A subnet mask is used to determine the network and host portions.

The Subnet Mask

• To identify the network and host portions of an IPv4 address, the subnet mask is compared to the IPv4 address bit for bit, from left to right.

• The actual process used to identify the network and host portions is called ANDing.

The Prefix Length

• A prefix length is a less cumbersome method used to identify a subnet mask address.

• The prefix length is the number of bits set to 1 in the subnet mask.

• It is written in “slash notation” therefore, count the number of bits in the subnet mask and prepend it with a slash.

Network, Host, and Broadcast Addresses

Within each network are three types of IP addresses:

• Network address

• Host addresses

• Broadcast address

Types of IPv4 Addresses

Special Use IPv4 Addresses

• Loopback addresses

  • 127.0.0.0 /8 (127.0.0.1 to 127.255.255.254)

  • Commonly identified as only 127.0.0.1

  • Used on a host to test if TCP/IP is operational.

• Link-Local addresses

  • 169.254.0.0 /16 (169.254.0.1 to 169.254.255.254)

  • Commonly known as the Automatic Private IP Addressing (APIPA) addresses or self-assigned addresses.

  • Used by Windows DHCP clients to self-configure when no DHCP servers are available.

Reasons for Segmenting Networks

• Subnetting reduces overall network traffic and improves network performance.

• It can be used to implement security policies between subnets.

• Subnetting reduces the number of devices affected by abnormal broadcast traffic.

• Subnets are used for a variety of reasons including by:

  • Location

  • Group or Function

  • Device Type

Subnet an IPv4 Network

• Diagram illustrating Network Prefix and Host ID.

Subnet on an Octet Boundary

Networks are most easily subnetted at the octet boundary of /8, /16, and /24.

Notice that using longer prefix lengths decreases the number of hosts per subnet.

Subnet within an Octet Boundary

Refer to the table to see six ways to subnet a /24 network.

VLSM Variable Length Subnet Mask

The left side displays the traditional subnetting scheme (i.e., the same subnet mask) while the right side illustrates how VLSM can be used to subnet a subnet and divided the last subnet into eight /30 subnets.

When using VLSM, always begin by satisfying the host requirements of the largest subnet and continue subnetting until the host requirements of the smallest subnet are satisfied.

The resulting topology with VLSM applied.

VLSM Variable Length Subnet Mask

With an ID range - 192.168.4.0/24 - Design an IP plan for the network using VLSM

VLSM Variable Length Subnet Mask

Example Scenario:

• LAN 2: 55 Hosts

• LAN 1: 25 Hosts

• LAN 3: 12 Hosts

• Link A, B, C: 2 Hosts

VLSM Variable Length Subnet Mask

VLSM Variable Length Subnet Mask

VLSM Variable Length Subnet Mask

VLSM Variable Length Subnet Mask

Business Continuity & Disaster Recovery

What is Business Continuity?

• A business continuity plan (BCP) is a strategic document that provides alternative modes of operation for business activities that, if interrupted, could result in a significant loss to the enterprise.

• Business continuity – An organisation’s ability to maintain operations after a disruptive event

• Examples of disruptive events:

  • Hurricane

  • Tsunami

  • Flooding

  • Earthquake

• Business continuity planning and testing steps:

  • Identify exposure to threats

  • Create preventative and recovery procedures

  • Test procedures to determine if they are sufficient

What is Business Continuity?

• Succession planning – Determining in advance who is authorised to take over if a key employee is unavailable, incapacitated or worse

• Business Impact Analysis (BIA)

  • Analyses the most important business functions and quantifies impact of their loss

  • Identifies threats through risk assessment

  • Determines impact if threats are realised

Data Storage redundancy Backups

• Data backup

  • Information copied to a different medium and stored at an offsite location so that it can be used in the event of a disaster

• Five basic questions that should be answered:

  • What information should be backed up?

  • How often should it be backed up?

  • What media should be used?

  • Where should the backup be stored?

  • What hardware or software should be used?

Data Backups (cont’d)

• Backup software can internally designate which files have already been backed up

  • By setting an archive bit in the properties of the file

• Backing up to magnetic tape has been the mainstay of data backups for over 30 years

• Cloud now has many advantages.

• Grandfather-father-son backup system

  • Divides backups into three sets: a daily backup (son), a weekly backup (father), and a monthly backup (grandfather)

Types of Data Backups

Storage Redundancy

• RAID (Redundant Array of Independent Drives)

  • Uses multiple hard disk drives for increased reliability and performance

• The most common levels of RAID are:

  • RAID Level 0 (striped disk array without fault tolerance)

  • RAID Level 1 (mirroring)

  • RAID Level 5 (independent disks with distributed parity)

  • RAID 0+1 (high data transfer)

Redundant Sites

• Redundancy can also be planned for the entire site itself

• Hot site

  • Generally run by a commercial disaster recovery service

  • Allows a business to continue computer and network operations to maintain business continuity

  • A hot site is essentially a duplicate of the production site and has all the equipment needed for an organization to continue running, including office space and furniture, telephone jacks, computer equipment, and a live telecommunications link. Data backups of information can be quickly moved to the hot site,

• Cold site

  • Provides office space but the customer must provide and install all the equipment needed to continue operations

Sites (cont’d)

• Warm site

  • Has all of the equipment installed but does not have active Internet or telecommunications facilities, and does not have current backups of data