Network Engineer

The most common types of cables used in networking: 

• Ethernet cable is the most common type of cable used in networking. It's typically used to connect computers, printers, and other devices to a router or switch. Ethernet cables come in various sizes, including CAT5, CAT5e, and CAT6. 

• Fiber optic cable is another common type of cable used in networking. It's typically used to connect routers and switches to each other, or to connect a router or switch to a central office. Fiber optic cables are made from thin strands of glass or plastic, and they can transmit data at much higher speeds than Ethernet cables. 
• Coaxial cable is another type of cable used in networking. It's often used to connect a modem to a router or switch. Coaxial cables are made from a copper core surrounded by insulation and a protective outer layer. They're typically thicker than Ethernet or fiber optic cables. 
• Twisted pair cable is another type of cable often used in networking. It consists of two insulated wires that are twisted around each other. twisted pair cables are typically used to connect devices to each other or to connect a device to a central office. They can be either shielded or unshielded, and they come in various sizes including CAT5, CAT5e, and CAT6. 

When you're configuring a device on a network, you will need to choose between using a static IP address or a dynamic IP address. Static IP addresses don't change, which means that you will need to configure the address manually. This can be helpful if you need to connect to a specific device on the network regularly.  

Dynamic IP addresses, on the other hand, are assigned automatically by a DHCP server. This can be easier to manage since you don't need to keep track of the changing IP addresses, but it can also be less reliable since the IP address can change at any time. When you're deciding which type of IP address to use, it's important to consider your needs and decide which option will be best for your network.

Frame Relay is a digital link layer protocol that allows multiplexing of voice and data circuits on a single link. It was developed to provide high-speed, low-cost data transport over digital links. Its main features include: 

• Virtual Circuits: Frame Relay uses virtual circuits (also known as logical connections or logical links) to connect devices. A virtual circuit is a connection between two endpoints that appears to be direct, even though it may be physically implemented over multiple paths. 
• Efficient Use of Bandwidth: Frame Relay is designed to make efficient use of bandwidth by supporting variable-length packets. Packets can be of any size up to the maximum transmission unit (MTU) configured on the link. 
• Committed Information Rate (CIR): The CIR is the guaranteed minimum information transfer rate from the service provider to the customer site. The CIR ensures that the customer site always has enough bandwidth for its needs, even during peak periods. 
• Frame Discard: If a Frame Relay device receives a packet that exceeds the CIR, it will discard the excess data. This helps to ensure that only packets that can be transmitted within the CIR are sent, making efficient use of available bandwidth.

Network cabling is the process of connecting various types of equipment in a network, including computers, servers, and storage devices. The most common type of cabling used for networking is Ethernet. Ethernet cable consists of two insulated copper wires that are twisted together to form a single cable. The twisted pair design helps to reduce interference from other cables and devices.  

Ethernet cables are typically classified by their speed and bandwidth capability. For example, Cat5 cable is capable of speeds up to 100Mbps and has a bandwidth of 100MHz. Cat6 cable is capable of speeds up to 10Gbps and has a bandwidth of 250MHz. When choosing a network cabling system, it is important to consider the future needs of the network. For example, if you anticipate adding more devices or increasing the bandwidth requirements of the network, you will need to choose a cabling system that can support those future needs.

The standard OSI model is known as 802.xx because it is the most commonly used model for networking. The 802.xx designation comes from the fact that it was originally developed by the IEEE (Institute of Electrical and Electronics Engineers). The 802.xx model is a 7-layer network model that is used to teach beginners about networking concepts. The 7 layers are: Physical, Data Link, Network, Transport, Session, Presentation, and Application. Each layer has its own set of protocols that must be followed in order for data to be transferred between two devices. The OSI model is also known as the TCP/IP model because it was developed after the TCP/IP protocols were created.

A MAC address is a unique identifier assigned to network interface cards (NICs). MAC addresses are used for identifying devices on a network and are usually assigned by the manufacturer. Each MAC address is composed of six octets, and is typically written as a string of 12 hexadecimal characters. For example, a MAC address might be written as 01:23:45:67:89:ab.

MAC addresses are usually stored in ROM on NICs, and can be configured manually or retrieved automatically from the firmware. In order for devices to communicate with each other on a network, they must have unique MAC addresses. If two devices have the same MAC address, they will not be able to communicate properly.

Forward lookup is the process of resolving an IP address to a hostname while reverse lookup is the process of resolving a hostname to an IP address. DNS servers use forward lookup when they receive a request from a client for a website's IP address. The DNS server then looks up the IP address in its database and returns it to the client.  

Reverse lookup is used when a DNS server needs to resolve a hostname to an IP address. For example, when a user types in a URL into their web browser, the DNS server will need to perform a reverse lookup to find the corresponding IP address. The DNS server will then return the IP address to the client so that the client can connect to the website.

TCP/IP is short for Transmission Control Protocol/Internet Protocol, and it is the suite of communication protocols used to connect hosts on the Internet. TCP/IP can be used in conjunction with a variety of higher-level protocols, such as HTTP, FTP, and SMTP, to support applications like web browsing, file transfer, and email. The TCP/IP protocol suite was developed in the 1970s by the US Department of Defense, and it is now the standard protocol for communicating between computers on the Internet.  

The TCP part of TCP/IP is responsible for ensuring that data is delivered correctly from one computer to another. When you request a web page in your browser, your computer sends a TCP packet to the web server. The web server then replies with another TCP packet, which includes the requested web page. If any of the packets are lost or corrupted in transit, the destination computer will request that the source computer retransmit the missing data.  

The IP part of TCP/IP is responsible for routing packets from their source to their destination across multiple networks. Every computer on the Internet has a unique IP address, which consists of four numbers separated by periods (e.g., 192.168.1.1). When you send a packet from your computer to another computer on the Internet, your computer will look up the destination IP address in a routing table and forward the packet accordingly.  

Most home users don't need to worry about TCP/IP, because it is typically configured automatically by your ISP (Internet Service Provider). However, if you're troubleshooting network problems or setting up a server, it's helpful to have a basic understanding of how TCP/IP works.

There are three main types of signal degradation that can occur in a network: attenuation, distortion, and noise. Attenuation is the loss of signal strength as it travels through the network. Distortion occurs when the signal is altered in some way, making it inaccurate. Noise is any interference that can corrupt the signal. All three of these factors can impair the quality of the signal and make it difficult to interpret.

To minimize these effects, engineers must carefully design the network to minimize loss and maximize reliability. In some cases, special equipment may be needed to filter out noise or boost the signal. By understanding the different types of signal degradation, engineers can ensure that networks are able to function at optimal levels.

A private network is a network that uses private IP addresses. Private IP addresses are not assigned to any specific organization and can be used by anyone. The most common private IP address ranges are 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. These address ranges are not routable on the public internet and can only be reached by devices on the same local network. A network engineer would typically use a private IP address range when setting up a LAN or WAN. Devices on a private network can communicate with each other without going through a public router, making it more secure and efficient than using a public IP address range.

NAT (Network Address Translation) is a method of mapping an entire network to a single IP address. This is typically done by a router, which will forward packets from the private network to the public network. NAT can be used to hide the IP addresses of devices on a private network, as well as to improve security by providing a barrier between the two networks. In order to understand how NAT works, it is first necessary to understand the different types of IP addresses.

There are three different types of IP addresses: private, public, and static. Private IP addresses are those that are assigned by a router to devices on a private network. Public IP addresses are those that are assigned by an ISP to devices on a public network. Static IP addresses are those that are assigned manually and do not change.

When a packet is sent from a device on a private network to a device on a public network, the router will use NAT to replace the private IP address with the public IP address. This will allow the packet to reach its destination without revealing the true IP address of the sending device. NAT can also be used to hide the true IP address of a server by using a static IP address.

In this case, all traffic from the server will appear to come from the static IP address, rather than the server's actual IP address. This can be used to improve security and avoid identification by hackers. NAT is an essential component of networking, and it is important for anyone working in this field to have a good understanding of how it works. 

In networking, bandwidth refers to the data transfer rate or the amount of information that can be transmitted in a given time period (usually measured in seconds). It's similar to how we often think of 'speed' in everyday life - how fast something is moving. In other words, bandwidth is a measure of how much data can flow through a connection at any given time. Just like the width of a pipe determines how much water can flow through it, the bandwidth of a network connection determines how much data can flow through it.  

For example, if you are downloading a large file from the internet, your bandwidth would determine how long it would take to download that file. If you have a narrower pipe (lower bandwidth), it will take longer to fill up and you'll get less water (data) per second. A wider pipe (higher bandwidth) will fill up faster and give you more water (data) per second. So when we talk about increasing someone's bandwidth, we mean giving them a higher data transfer rate so they can do more things at once or do things faster.

While there are many factors to consider when choosing the best path for data packets, there are three key criteria that network engineers typically focus on: latency, load balancing, and cost. Latency, or the amount of time it takes for a packet to travel from its source to its destination, is often the most important factor, particularly for real-time applications like VoIP or video streaming.  

Load balancing is also important to ensure that no single link in the network becomes overloaded and causes delays; this can be accomplished through either static routing, which manually determines the best path for each type of traffic, or dynamic routing, which automatically updates the routing table in response to changes in network conditions. Finally, cost is always a consideration when selecting a path, as using multiple links with higher capacity may be more expensive than using a single link with lower capacity. By taking all of these factors into account, network engineers can select the best path for data packets and ensure that networks run smoothly and efficiently.

RAS, or remote access services, refer to a type of service that allows users to connect to a network from a remote location. RAS is commonly used in corporate environments, where employees may need to access company resources from outside the office. In order to set up RAS, a network administrator will typically configure a server with the appropriate software and hardware.  

Once the server is configured, users can connect to it using a variety of methods, such as a dial-up modem or a VPN client. RAS can be an essential tool for businesses, but it's important to note that it can also be misused. For example, some employees may use RAS to access company resources for personal gain. As a result, it's important for businesses to carefully monitor their RAS usage and put appropriate safeguards in place.

A firewall is a critical component of any network security strategy. It acts as a barrier between your internal network and the outside world, allowing you to control what traffic is allowed in and out. In order to understand how a firewall works, it is important to first understand the basics of networking. Networks consist of a series of interconnected devices, such as computers, routers, and switches. Each device has a unique IP address that is used to identify it on the network.  

When data is sent from one device to another, it is broken up into small packets. Each packet contains the sender's IP address, the recipient's IP address, and the data being transferred. Firewalls work by inspecting each packet that comes through and comparing it to a set of rules. If the packet meets the criteria laid out in the rules, it is allowed through. If not, it is blocked. This ensures that only authorized traffic is allowed onto your network.

Access Control Lists are used to define what type of traffic is allowed into or out of a network. Standard ACLs use only the source IP address to make decisions about whether to allow traffic, while extended ACLs can also use information such as port numbers and protocols.  

As a result, extended ACLs are much more flexible and can be used to create very specific rules about what types of traffic are allowed. For example, an extended ACL could be used to allow all HTTP traffic from a specific IP address, while blocking all other traffic from that same address. However, because they are more complex, extended ACLs can also be more difficult to configure and manage. As a result, they are typically only used when absolutely necessary.

Netstat is a command-line network utility that can be used to view all of the active network connections on a computer. The netstat utility can be used to view both incoming and outgoing network traffic, and it can also be used to view detailed information about specific connections. When used with the appropriate options, netstat can also be used to view information about the routing table, interface statistics, and much more.  

For beginners, netstat can be a useful tool for understanding the basic structure of a network and for troubleshooting potential connectivity issues. With a little practice, netstat can be an extremely powerful tool for managing and troubleshooting networks.

Proxy servers sit between clients and servers, acting as a go-between for requests from clients seeking resources from servers. A client connects to the proxy server, requesting some service, such as a file, web page, or other resource available from a different server. The proxy server evaluates the request according to its filtering rules. If the request is validated, the proxy server forwards it to the remote server where the requested resource lives.  

When the remote server responds, the proxy server sends the response back to the client. In this way, proxy servers can act as a firewall by filtering traffic and blocking requests that do not meet its criteria. Proxy servers can also improve performance by caching resources that have been previously requested. When a client requests a resource that has already been cached by the proxy server, there is no need to send a request to the remote server since the proxy already has a copy of the desired resource.  

This can save time and improve response times for subsequent requests.Proxy servers are an important part of many computer networks, providing security and performance enhancements that can be essential for a well-functioning network.

When it comes to securing a computer network, there are a few key measures that any network engineer should take. First, it is important to understand the network layout and identify any potential weak points. Second, all devices on the network should be properly configured and secured, with strong passwords and up-to-date security software. Third, regular backups should be made of all critical data, in case of an accident or attack. Finally, it is also beneficial to monitor the network for unusual activity, and to have a plan in place for how to respond in the event of a security breach. By taking these steps, it is possible to greatly reduce the risks to a computer network.

TELNET is a network protocol that allows for remote control of another computer. It is commonly used by system administrators to manage servers from afar, but it can also be used by hackers to gain unauthorized access to systems. TELNET works by establishing a connection between two computers and then allowing the user to issue commands as if they were working directly on the target system. This can be done either through a text-based interface or via a graphical interface.  

TELNET is not a secure protocol, so it is important to take precautions when using it. For example, it is advisable to use TELNET only over an encrypted connection such as SSH. Additionally, users should be aware of the potential for Man-in-the-Middle attacks and take steps to protect themselves accordingly.