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The Network Time Protocol (NTP) is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks. NTP is designed to synchronize the clocks on computers and networks across the Internet or Local Area Networks (LANs).  NTP analyses the timestamp values including the frequency of errors and the stability. A NTP server will maintain an estimate of the quality of its reference clocks and of itself. Network Time Protocol - NTP How to Synchronize NTP with time? NTP server usually receives its time from a trustworthy time source, such as a radio clock attached to a time server, and then distributes this time across the network. NTP is extremely efficient and there is no more than one packet per minute is necessary to synchronize two machines to within a millisecond of each other The NTP client initiates a time-request exchange with the NTP server. As a result of this exchange, the client is able to calculate the link delay

AAA refers to Authentication, Authorization and Accounting. It is used to refer to a family of protocols that mediate network access. Two network protocols providing this functionality are particularly popular: the RADIUS protocol, and its newer Diameter counterpart. The administrator can take an access to a router or a device through console but it is very inconvenient if someone is sitting far from the place of that devices, so eventually he has to take remote access to that device. But as the remote access will be available by using an IP address therefore it is possible that an unauthorized user can take access using that same IP address therefore for security measures, we have to put authentication. Also, the packets exchange between the devices should be encrypted so that any other person should not be able to capture that sensitive information. Therefore, a framework called AAA is used to provide that extra level of security. AAA Authentication Authentica

DNS - Domain Name System The DNS (domain name system) is a network system of servers that translates numeric IP addresses into readable, hierarchical Internet addresses, and vice versa. This is what allows your computer network to understand that you want to reach the server at 192.168.100.1 (for example) when you type into your browser a domain name such as www.netwyman.com DNS - Domain Name System The task for DNS, Domain Name System, in this regard is to translate the domain name into an IP address. When a website is accessed a DNS lookup is performed which generates the IP address of the server hosting the website. A query is then sent to the IP address and the website comes back as the answer to the query. DNS is used by virtually every device connected to the Internet, it is a common target of hacker attacks. Examples include DNS cache poisoning, DNS spoofing, and buffer overflow attacks transmitted through DNS commands. There is two methods to control DNS traffic throu

VRF - Virtual Routing Forwarding Virtual routing and forwarding (VRF) is a technology included in IP (Internet Protocol) network routers that allows multiple instances of a routing table to exist in a router and work simultaneously. This increases functionality by allowing network paths to be segmented without using multiple devices. Because traffic is automatically segregated, VRF also increases network security and can eliminate the need for encryption and authentication. Internet service providers (ISPs) often take advantage of VRF to create separate virtual private networks (VPNs) for customers; thus the technology is also referred to as VPN routing and forwarding. VRF - Virtual Routing Forwarding The VRF device combined with ip rules provides the ability to create virtual routing and forwarding domains (aka VRFs, VRF-lite to be specific) in the Linux network stack. One use case is the multi-tenancy problem where each tenant has their own unique routing tables and in the ver

WiFi Protected Access WPA is a security protocol designed to create secure wireless (Wi-Fi) networks. It is similar to the WEP protocol, but offers improvements in the way it handles security keys and the way users are authorized. Wifi Protected Access WPA referred to as the draft IEEE 802.11i standard became available in 2003. The Wi-Fi Alliance made it as an intermediate measure in anticipation of the availability of the more secure and complex WPA2, which became available in 2004 which is a common shorthand for the full IEEE 802.11i (or IEEE 802.11i-2004) standard. For an encrypted data transfer to work, both systems on the beginning and end of a data transfer must use the same encryption/decryption key. While WEP provides each authorized system with the same key, WPA uses the temporal key integrity protocol (TKIP), which dynamically changes the key that the systems use. This prevents intruders from creating their own encryption key to match the one used by the secure network

Zero touch provisioning or so called ZTP is the way to automatic configuration on Cisco vEdge devices for which almost zero manual intervention required. If we talk about the Zero touch provisioning, Networking traditionally has been a complex and manual for IT. The advent of SDN changed it all. Out of all benefits of SD-WAN, ZTP is among the top three. With ZTP, networking is automated and an intent driven process. Zero touch provisioning is a switch, that simplifies provisioning and configuration of devices automatically without any manual intervention. The switch (ZTP) downloads and runs the centrally stored configuration, which it acquires by sending a request through DHCP or TFTP. ZTP seamlessly allows IT to update OSs, deploy patches and bug fixes and embed additional features prior to connection. Using Scripts, ZTP can also connect to configuration management platforms or a custom tool. ZTP relies on below service which are: A license file provided by Cisco for overlay net

Gateway Load Balancing Protocol (GLBP) is a Cisco proprietary protocol that attempts to overcome the limitations of existing redundant router protocols by adding basic load balancing functionality. In addition to being able to set priorities on different gateway routers, GLBP allows a weighting parameter to be set. Gateway Load Balancing Protocol Gateway Load Balancing Protocol (GLBP) is one of First Hop Redundancy Protocol (FHRP) which provides redundancy like other First Hop Redundancy Protocol, also provides load Balancing. It is a Cisco proprietary protocol which can perform both functions. It provides load Balancing over multiple routers using single virtual IP address and multiple virtual Mac address. GLBP allow automatic selection and simultaneous recovery from first hop router failures. GLBP provides load balancing over multiple (router) gateways using a single virtual IP address and multiple virtual MAC addresses. The bandwidth/traffic load is shared between multiple ro