Persistent Systems NOC Engineer 1 Interview Questions and Answers

VLAN stands for Virtual Local Area Network, used to logically segment a network.

• VLANs help in improving network performance and security by isolating traffic.

• They allow multiple networks to coexist on the same physical infrastructure.

• VLANs are configured at the switch level and can span multiple switches.

• Each VLAN has its own broadcast domain, reducing unnecessary network traffic.

• VLANs are identified by a VLAN ID (VID)

BGP attributes are used to influence the path selection process in BGP routing.

• BGP attributes include AS_PATH, NEXT_HOP, LOCAL_PREF, etc.

• AS_PATH is a list of AS numbers that the route has traversed.

• NEXT_HOP is the IP address to reach the next hop towards the destination.

• LOCAL_PREF is used to influence outbound traffic.

• MED (Multi-Exit Discriminator) is used to influence inbound traffic.

• Weight is a Cisco-specific attribu...read more

To troubleshoot BGP going down, check BGP neighbor status, analyze BGP routing table, verify BGP configuration, and check for any network connectivity issues.

• Check BGP neighbor status to see if the neighbors are up and if there are any flaps

• Analyze BGP routing table to identify any inconsistencies or missing routes

• Verify BGP configuration for any errors or misconfigurations

• Check for any network connectivity issues such

OSPF formation involves states like Down, Init, 2-Way, Exstart, Exchange, Loading, Full.

• Down state: Initial state when OSPF process is not running.

• Init state: OSPF process is starting up.

• 2-Way state: Routers have exchanged hello packets and are now neighbors.

• Exstart state: Master and slave routers are determined.

• Exchange state: Database description packets are exchanged.

• Loading state: Link-state advertisements are exch...read more

OSPF LSA types include Router LSA, Network LSA, Summary LSA, and ASBR Summary LSA.

• Router LSA (Type 1) - Generated by all routers and contains information about directly connected links.

• Network LSA (Type 2) - Generated by DR to advertise the network segment.

• Summary LSA (Type 3, 4, 5) - Generated by ABR to advertise routes to other areas.

• ASBR Summary LSA (Type 4) - Generated by ABR to advertise ASBR information to other