Interview Questions and Answers

Overlay is a network virtualization technique that adds a layer of abstraction over the physical network, while underlay refers to the physical network infrastructure.

• Overlay is used to create virtual networks on top of the physical network infrastructure.

• Underlay refers to the physical network infrastructure that provides connectivity between devices.

• Overlay networks are used to provide network virtualization, multi-tenancy, and network segmentation.

• Underlay networks are res...read more

The cost of default route varies depending on the network infrastructure and service provider.

• The cost of default route is usually included in the overall cost of the internet service provided by the ISP.

• The cost may also depend on the type of connection, such as fiber optic or cable.

• In some cases, the cost may be higher for businesses that require more bandwidth and faster speeds.

• The cost may also vary depending on the location and availability of the service provider.

• It is ...read more

OSPF neighbourship occurs when two OSPF routers establish a relationship to exchange routing information.

• OSPF routers send hello packets to discover neighbours

• If the hello packets are compatible, the routers become neighbours

• The routers exchange database descriptors to synchronize their link-state databases

• If the databases are the same, the routers become fully adjacent

• Neighbourship can be affected by network topology changes or misconfigurations

VRF stands for Virtual Routing and Forwarding. It is a technology that allows multiple instances of a routing table to coexist on the same router.

• VRF provides logical separation of routing tables, allowing multiple routing domains to exist on a single physical router.

• Each VRF has its own routing table and forwarding table, which allows for overlapping IP addresses to be used without conflict.

• VRFs are commonly used in MPLS networks to provide VPN services.

• VRFs can be configure...read more

AS path prepend is a technique used in BGP to influence the path selection of traffic.

• AS path prepend involves adding the same AS number multiple times to the AS path attribute of a BGP route advertisement.

• This makes the path appear longer and less desirable, causing traffic to prefer other paths.

• AS path prepend can be used to influence inbound or outbound traffic.

• Inbound traffic can be influenced by adding the local AS number multiple times to the AS path of routes advertise...read more

SDWAN is a software-defined approach to managing and optimizing WAN connections.

• SDWAN uses software to control and manage network traffic across multiple WAN connections.

• It can dynamically route traffic based on network conditions and application requirements.

• SDWAN can improve network performance, reduce costs, and simplify network management.

• Examples of SDWAN vendors include Cisco, VMware, and Silver Peak.

BGP damping is a technique used to reduce the impact of unstable routes on the internet.

• BGP damping helps to prevent the propagation of unstable routes by temporarily suppressing them.

• It is used to reduce the impact of route flapping, which occurs when a route repeatedly alternates between available and unavailable states.

• BGP damping assigns a penalty value to unstable routes, and if the penalty exceeds a certain threshold, the route is suppressed.

• The penalty value decreases ...read more