| Explain layer 1 (Physical) layer of the OSI model. | Layer 1 (The physical layer) of the OSI model refers to physical media such as wires, connections and hubs. NIC's can be placed in this layer but they actually belong in layer 2 as they are work phyical (MAC) addressing. |
| Explain layer 2 (Data link) layer of the OSI model. | Layer 2 of the OSI model, the data link layer deals with network communications between the physical layer and the network layer it is sub-divided into the MAC (media access control) and LLC (logical link control). it deals with multiplexing data streams and data frame detection. Switches operate on this layer. |
| Explain layer 3 (Network) layer of the OSI model. | Layer 3 (Network layer) deals with network communication based on logical addressing such as IP addresses. Devices such as router operate on this level as they can understand logical data to route data packets and segment networks. |
| Explain layer 4 (Transport) layer of the OSI model. | Layer 4 (Transport layer) is everything to do with TCP/IP, UDP transmitting the data packets across the network using ports and protocols. |
| Explain layer 5 (session) layer of the OSI model. | Layer 5 (session) of the osi model deals with establishes, manages and terminates the connections between local and remote application. This is where things such as password authenticaltion and point to point tunnelling occur. |
| Explain layer 6 (Presentation) of the OSI model. | Layer 6 (presentation layer) this layer is responsible for formatting and delivery of information to the application layer, it deals with encryption and translation of data packets. |
| Explain layer 7 (Application) of the OSI model. | Layer 7 or the Application layer is where the user interface resides. It is wholly application specific. |
| Explain broadcast domains. | A broadcast domain is a logical division of a computer network where all nodes can reach each other by broadcast at the data link layer. |
| Explain CSMA/CD. | Carrier sense multiple access / collision detection is a MAC protocol that monitors the network, detects when a collision occurs. It will then wait a random amount of time before resending the data packet. |
| Explain CSMA/CA. | Carrier sense multiple access / collision avoidance. Used over wireless networks intent to transmit is sent responded to with an aknowledgment. Then the data is sent and avoids collision. |
| Explain Collision domains. | A collision domain is a network segment connected by shared media where simultaneous transmissions can result in collisions. |
| Explain protocol data units. | a PDU is a block of information passed over the network. through the OSI layer it is 1. raw bits (1s and 0s) 2. frames 3. packets 4.segments with a tcp header. 5. The data passed to network connection. 6. The data formatted for presentation. 7. The data for a software application. |
| What is an MTU? | MTU = maximum transmission unit. The biggest size a packet or frame can be to be sent over the network. |
| What is a broadcast. | A broadcast is when one node on the network transmits its message to all other nodes within its broadcast domain. |
| What is a multicast? | A multicast is when a node sends its message across the network to multiple specific nodes based on an addressing scheme. |
| What is unicasting? | Unicasting is sending a transmission to only one other node using a point to point connection. |
| Summarise VLANs. | Virtual local area networks can be configured within a network for security, by partitioning your network. you can also improve your network performance by creating VLANS to group devices that communicate with each other most often. |
| Explain trunking 802.1Q. | Trunking is a protocol used by switches to be able to carry data from multiple vlans (while keeping the vlan information) over the same media connection and then deliver back to its seperate VLAN. |
| Explain tagging and untagging ports. | A tagged (trunked) port is configured to allow data from many VLANs while an untagged or access port will only recieve data for a specific VLAN. |
| Port mirroring. | port mirroring also known as SPAN (switch port analyzer) is configured so that a switch will send a copy of all data sent to one port (or even an entire VLAN) to another port so that it can be analyzed. |
| Explain switching loops and spanning tree. | A switching loop can occur when there is more then 1 connection between multiple layer 2 devices. The devices will send a packet of information back and fourth over these connections which can result in a broadcast storm. STP is a link management protocol that provides redundancy and prevents loops. |
| Explain PoE 802.3af and PoE+ 802.3at | Power over ethernet or 802.3at provides a max of 15.4 watts over the ethernet cable removing the need for a dedicated power cord, it is used to power devices such as phones and wifi. PoE+ or 8023af can provide 25.5 watts and supports things such as surveillance cameras, alarm systems and video IP phones. |
| Explain DMZ. | A demilitarized zone is a security feature of a network where certain devices in the network are positioned logically or physically outside the private network with the used of a firewall. external facing devices such as web developers are placed here to be accessed by untrusted networks such as the internet. |
| What is a MAC address table. | A MAC address table is the table of addresses that switches will collect to determine where to forward traffic on a LAN. |
| What is an ARP table. | An arp table is used to correlate the networks MAC addresses with corresponding IP addresses. |
| Explain ipv4 and ipv6. | Ipv4 and ipv6 are IP addressing methods using binary. ipv4 is made up of 32bit addresses using 0-9 separated by periods. ipv4 provides 4.3 billion addresses. ipv6 addresses are 128 bit addresses using 0-9,a-f to provide hexadecimal addresses separated by colons. ipv6 provides 340 undecillion addresses. |
| Explain RIP. | The routing information protocol is an old distance vector routing protocol, it employs the "hop" count (1 router in a path = 1 hop) as a routing metric. RIP prevents routing loops by implementing a limit to the number of hops allowed in a path from source to destination. |
| Explain EIGRP. | Enhanced interior gateway routing protocol is an advanced routing vector protocol, created by cisco. It is used for automating routing decisions and configuration. |
| What is OSFP? | open shortest path first is a link state routing protocol within the interior gateway protocols group. Uses a LSR ( link state routing algorithm) to determine the shortest path over the network. |
| What is BGP? | Border gateway protocol is a standardized exterior gateway protocol design to exchange routing and reachability information between autonomous systems on the internet. |
| Explain static routing. | Static routing is routing using a manually configured static address instead of one assign dynamically. In many cases static addresses are configured by a network admin. but this is not always the case. |
| Explain dynamic routing. | Dynamic routing is when a router sends packets via different routes as per the changes happening in the network. Dynamic routing uses protocols such as RIP, EIGRP and BGP. |
| Explain default routing. | Default routing occurs when no other route is available for an ip destination address. If the subnet for the destination is not in a routers routing table it will just send the packet over the default path which is usually to another routing device. This next device will perform the same steps until the packets finds its destination. |
| Explain ipv6 addressing. | ipv6 addressing uses 128 bit addresses. A hexadecimal number correlates to 4 bits, therefore an 1pv6 address is made up of 32 hexadecimal numbers. These numbers are split into 8 groups of 4 separated by colons. |
| Explain ipv6 tunnelling. | ipv6 tunnelling provides a way to route ipv6 traffic over an ipv4 architecture. ipv6 packets are encapsulated within ipv4 packets and then carried over the ipv4 topology. |
| Explain ip dual stack. | Dual stack means that devices on layer 2 and layer 3 are capable of simultaneously reaching both ipv4 and ipv6 proving a very flexible coexistence strategy. |
| Explain router advertisement. | RADVD router advertisement DAEMON is used for ipv6 auto configuration and routing. Routers periodically and in response to solicitation sends out messages for host to use to learn the prefixes and parameters of the local network. |
| Explain traffic shaping. | Traffic shaping is a bandwidth management technique that delays the flow of certain types of network packets in order to ensure network performance for high priority applications. |
| What is QoS? | Quality of service is any technology that manages data traffic to reduce packet loss, latency and jitter. Traffic is managed by setting network priorities. |
| Explain Diffserv. | Using Diffserv in your network allows you to configure relevant parameters onto switches and routers. Allows you to control what traffic is accepted and what traffic is discarded. |
| What is CoS? | Class of service is a parameter used in data and voice protocols to differentiate the types of payloads contained in the payloads being transmitted. The objective being to assign priorities to the payload or access levels to a telephone call. |
| Explain NAT/PAT | Network address translation / port address translation. In NAT private ip addresses are translated into public ip addresses. in PAT private ip addresses are translated in public ip addresses via port numbers. |
| Explain port forwarding. | Port forwarding is a behind the scenes process of intercepting data heading for a computers ip/port and redirecting it to a different ip and/or port. An application running on a computer can do this or a device within the network such as a router or a firewall. |
| Access control list | ACL is a table that tells a computers OS which access rights each user has to a particular system object such as a file directory or a file. standard ACLs filter based on ip address while extended ACLs filter based on the ip destination aswell as the source. |
| Explain distributed switching. | An architecture in which multiple process-controlled switching units are distributed. There is usually a centralized host switch and multiple distributed remote switches closer to concentrations of users. |
| What is the difference between packet switched and circuit switched networks? | Packet switching breaks data up into smaller blocks and sends them over the network, the can go in any path available. Circuit switching is used for telephone connections, 1 physical connection is made between phones which all data passes through. |
| Explain software defined networking. | Software defined networking is a network architecture approach that allows the network to be intelligently, centrally controlled or "programmed using software applications. This help operators manage the whole network consistently and holistically regardless of the underlying network technology. |
| Explain private vs public ip addresses. | Public ip addresses allow you to communicate and connect over the internet. Private ip addresses allow you to communicate over the private network but not connect to the public internet. |
| What is TCP/IP? | TCP/IP ( Transmission control protocol/ internet protocol) is a communications architecture used for networking computers and communicating over the internet. Used when reliability of packets is a priority. e.g. SMTP (e-mail), secure shell (SSH). |
| What is UDP? | UDP (User datagram protocol) like TCP/IP is a communications architecture. It differ from TCP/IP as it is faster but less reliable as it does not implement any error prevention. Used for things such as streaming and VoIP. |
| Explain functions and applications of a router. | A networking device operating on the Network layer (3) of the OSI model. Used to connect 2 or more networks using logical addressing, segmenting large networks into smaller more manageable subnets. Forwards data packets between computer networks and the internet. |
| Explain the function and application of a switch. | A networking device operating on the datalink layer (2) of the OSI model. Via multi data cables a switch allows multiple hosts to communicate over a network, switches manage the flow of data by only delivering data packets to the host/s to which they were intended using physical addresses. Often used in multiples for redundancies to prevent looping. |
| Explain the function and application of a Multilayer switch. | A networking device operating on the datalink layer (2) all the way to the application layer (7). Using Application specific integrated software (ASIC) hardware to route packets of data. They provide ease of use as they are configured automatically. Performing both switching and routing on the same platform provides faster connectivity such as is used for intranets or multimedia apps. |
| Explain the function and application of a firewall. | A firewall is a network security device that examines incoming and outgoing traffic and decides whether to allow or block network traffic based on a pre-determined set of security rules. |
| Explain the function and application of HIDS. | Host-based intrusion detection systems (HIDS) monitor processes and applications running on devices such as servers or workstations. HIDS tracks changes made to registry settings and critical system configuration. Alerts to any unauthorised or anomalous activity. |
| Explain the function and application of IDS and IPS. | Intrusion detection system and intrusion prevention system, continuously monitor your network, identifying and incidence, logging information, stopping the intrusion and alerting the security administrators. |
| Explain the function and application of access points (wireless/ wired). | A networking sub-device in a LAN that allows devices to connect in another location, also provides for expanded bandwidth allowing more devices to connect to the network. |
| Explain the function and application of a content filter. | A content filter is a program that screens and excludes from access or availability web pages or emails that are deemed objectionable. NSFW. |
| Explain the purposes and use of SSH. | Secure shell (22) is a network protocol that allows one computer to connect to another computer over an unsecured network like the internet by having a shared agreement of how to communicate. This allows you to do things such as control servers remotely. |
| Explain the purposes and use of DNS. | The Domain name system (53) syncs up domain names with addresses giving the ability for humans to use memorable domain names, while computers on the internet can use IP addresses. |
| Explain the purposes and use of SMTP. | Simple mail transfer protocol (25) is a networking protocol that is in control of receiving and sending email. An SMTP server processes your email decides which server to send the message to and relays the message. |
| Explain the purposes and use of SFTP. | Secure file transfer protocol (23) is a secure way to send files from one machine to another. using encryption securely move files without them being readable. Authentication prevents unauthorised file access during the process. Access can require, User id and password. Also SSH keys can be generated and applied beforehand. |
| Explain the purposes and use of FTP. | File transfer protocol (20,21) used to transfer files from computer account to account, from an account to a desktop pc or access online software archives. |
| Explain the purposes and use of TFTP. | Trivial file transfer protocol (69) is used for simple file transfer that anyone can access as it forgoes any authentication and transfers over UDP. Primarily used for reading and writing files using a remote server. |
| Explain the purposes and use of telnet. | Telnet (23) is a type of client-server protocol used to open a command line on a remote computer such as a server. Superseded by SSH as it is more secure. |
| Explain the purposes and use of DHCP. | Dynamic host configuration protocol (67, 68) dynamically assigns IP addresses along with other network configuration parameters to devices so they can communicate with other IP networks. |
| Explain the purposes and use of HTTP. | Hyper-text transfer protocol (80) is a system used by computers, smart phones, tablets, etc. to communicate over the internet. For example use HTTP to ask a web server to send contents of a web page or to send data via online forms. |
| Explain the purposes and use of HTTPS. | Hyper-text transfer protocol (443) is a system used by computers on the web where security is paramount such as internet banking or online shopping. Relies on Transfer layer security (TLS) encryption to secure connections. |
| Explain the purposes and use of SNMP. | Simple network management protocol (161) is a set of standards for communicating with devices on the TCP/IP network. Used to manage network devices such as switches, routers and printers. SNMP can be used to monitor and configure these devices. |
| Explain the purposes and use of RDP. | Remote desktop protocol (3389) can be used to access a physical device or an application and control it as though you were doing it locally. |
| Explain the purposes and use of NTP. | Network time protocol (123) is intended to synchronize devices on the network to within a few milliseconds of the coordinated universal time (UTC) NTP design to mitigate the effects of variable network latency. |
| Explain the purposes and use of SIP. | Session initiation protocol (5060,5061) is a layer 7 protocol that establishes, modifies and terminates multimedia sessions such as VOIP and multimedia sessions. |
| Explain the purposes and use of SMB. | Server message block (445) is a communication protocol used to provide shared access to files, printers and serial ports. |
| Explain the purposes and use of POP. | Post office protocol 3 (110) retrieves emails from a server for a host application such as outlook. A POP server sets up directories or folders for each email account. |
| Explain the purposes and use of IMAP. | Internet message access protocol (143) Accesses email over the network. It is similar to POP but it does not create a directory or folder for your mail, it simply accesses your mail via a remote web server. |
| Explain the purposes and use of LDAP. | Lightweight directory access protocol (389) is a client/server protocol used to access and manage directory information. It reads and edits directories over IP networks and runs directly over TCP/IP using simple string formats for data transfer. |
| Explain the purpose and use of LDAPS. | Lightweight directory access protocol over TLS/SSL (636) allows for encryption of LDAP data including credentials protecting against credential theft. |
| Explain the purpose and use of H.323. | H.323 (1720) is a port that provides standards for computers communicating over packet based networks such as VOIP. specifies transmission protocols. |
| Explain the purpose and use of IP protocol type. | Used for relaying datagrams across network boundaries, its routing function allows internetworking and establishes the internet. |
| Explain the purpose and use of ICMP. | Internet control message protocol used by network devices to diagnose communication issues. Mainly used to determine whether data is reaching its intended destination in a timely manner. e.g. Ping and Traceroute. |
| Explain the difference between connection-oriented and connectionless networks. | connection-oriented networks work like a phone call whereas both parties establish a connection communicate and then terminate the connection. Connectionless networks are more like the post system as one party send the information and hopes it reaches its destination. Connectionless networking is done over UDP is fast but less reliable and more susceptible to congestion and data loss. |
