Network Engineer Interview

OSI Model

A 7-layer model explaining how data moves across a network.

Physical Layer

The layer that deals with cables and signals.

Data Link Layer

The layer responsible for MAC addresses and switching.

Network Layer

The layer that handles IP addressing and routing.

Transport Layer

The layer dealing with TCP/UDP and ports.

Session Layer

The layer responsible for session management.

Presentation Layer

The layer that handles encryption and data formatting.

Application Layer

The layer for user-facing applications such as HTTP and FTP.

TCP

Reliable, connection-oriented protocol.

UDP

Faster, connectionless protocol that is not reliable.

MAC Address

A unique hardware address assigned to a network interface.

IP Address

Identifies a device on a network; IPv4 is 32-bit, IPv6 is 128-bit.

Subnetting

Dividing a network into smaller networks to improve performance and security.

Public IP

An IP address that is internet-facing.

Private IP

An IP address used within an internal network.

NAT (Network Address Translation)

Translates private IP addresses to public IP addresses.

Static IP

An IP address that is manually configured.

Dynamic IP

An IP address that is assigned by DHCP.

ARP (Address Resolution Protocol)

Maps IP addresses to MAC addresses.

Default Gateway

The router that connects the local network to other networks.

Hub

A device that broadcasts to all connected devices.

Switch

A device that uses MAC addresses to send data only to the intended recipient.

Router

A device that uses IP addresses to route data between networks.

VLAN (Virtual Local Area Network)

A logical separation of networks within the same switch.

VLAN Tagging

Adding a VLAN ID to frames for identification.

Trunking

Carrying multiple VLANs between switches.

STP (Spanning Tree Protocol)

A protocol that prevents network loops.

Access Port

A port configured for one VLAN.

Trunk Port

A port that carries multiple VLANs.

Port Security

Limits which MAC addresses can connect to a switch port.

VTP (VLAN Trunking Protocol)

A protocol that manages VLANs across switches.

Switch Loop

A scenario that causes a broadcast storm if STP is disabled.

Broadcast Storm

Excessive broadcast traffic that can slow down or crash a network.

Routing

The process of selecting the best path for data across networks.

Static Routing

Routing that is manually configured.

Dynamic Routing

Routing that uses protocols to automatically determine paths.

RIP (Routing Information Protocol)

A slow routing protocol.

OSPF (Open Shortest Path First)

A fast and scalable routing protocol.

EIGRP (Enhanced Interior Gateway Routing Protocol)

A proprietary Cisco routing protocol.

Routing Table

A list of known routes in a networking device.

Administrative Distance

The trust level assigned to routing sources.

IGP (Interior Gateway Protocol)

A routing protocol used within an autonomous system.

EGP (Exterior Gateway Protocol)

A routing protocol used between different autonomous systems.

Purpose of Routing Protocol

To learn and update network routes automatically.

BGP (Border Gateway Protocol)

The primary protocol used for internet routing.

Route Summarization

The process of combining multiple routes into a single route.

Inter-VLAN

Routing between different VLANs.

Intra-VLAN

Routing within the same VLAN.