CompTIA Network + Routing

Router

Forwards traffic between subnets, between an internal and external network, or between two external networks

Routing Table

Helps determine which route entry is the best fit for the network

Router

Forwards traffic between subnets, between an internal and external network, or between two external networks

Routing Table

Helps determine which route entry is the best fit for the network

Directly Connected Route

Learned by physical connection between routers

Static Route

Manually configured by an administrator

Dynamic Route

Learned by exchanging information between routers

Split Horizon

Prevents a route learned on one interface from being advertised back out of that same interface

Poison Reverse

Causes a route received on one interface to be advertised back out of that same interface with a metric considered to be infinite

Interior Gateway Protocol (IGP)

Operates within an autonomous system

Exterior Gateway Protocol (EGP)

Operates between autonomous systems

Distance Vector

Sends full copy of routing table to its directly-connected neighbors at regular intervals

Hold-down Timer

Prevents updates for a specific period of time and speeds up convergence

Hop Count

Number of routers from the source router through which data must pass to reach the destination network

Link State

Requires all routers to know about the paths that all other routers can reach in the network

Routing Information Protocol (RIP)

A distance vector protocol that uses hop count (maximum hops of 15; 16 is infinite)

Open Shortest Path First (OSPF)

Link state protocol that uses cost

Intermediate system to Intermediate System (IS-IS)

Link state protocol that also uses cost and functions like OSPF protocol, but not as widely popular

Enhanced Interior Gateway Routing Protocol (EIGRP)

Hybrid of distance vector and link state protocols that uses bandwidth and delay

Border Gateway Protocol (BGP)

Path vector that uses the number of autonomous system hops instead of router hops

Route Selection

Determines which path a router could take

Administrative Distance (AD)

Lower AD is considered more believable or trustworthy

Network Address Translation (NAT)

Used to conserve the limited supply of IPV4 addresses

Dynamic Nat (DNAT)

Automatically assigns an IP address from a pool and gives a one-to-one translation

Static Nat (SNAT)

Manually assigns an IP address and gives a one to one translation

Port Address Translation (PAT)

Sharing of one public IP by multiple private OP addresses which gives a many-to-one translation

Routing Redundancy Protocol

Network Protocol that prevents disruptions in communication by automatically rerouting data traffic in case of a path or device failure

First Hop Redundancy Protocol (FHRP)

Set of protocols designed to ensure network reliability by providing automatic failover to a backup router to maintain uninterrupted network service

Reliability

Ensures that communications remain up and running even if a single router configuration fails

Load Balancing

Distributes network traffic across multiple routers to prevent any single device from being overwhelmed

Seamless Transitions

Sends data from a failed router to redirect to a standby router

Virtual IP

Ip address that is not bound to a specific device but serves as a representative for one or multiple devices

Subinterface

Allows a single physical interface on a router or a switch to be subdivided into multiple logical interfaces

Hot Standby Router Protocol (HSRP)

Developed by Cisco as a redundancy protocol that can establish a fault-tolerant default gateway for devices on a local network segment

Virtual Router Redundancy Protocol (VRRP)

Standard redundancy protocol that functions similarly to the HSRP, with few key differences

Gateway Load Balancing Protocol (GLBP)

Cisco-developed protocol that take redundancy by adding load balancing capabilities into the mix

Multicast Routing

Multicast sender sends traffic to a Class DIP address, known as a multicast group

Internet Group Management Protocol (IGMP)

Used by clients and routers to let the routers know which interfaces have multicast receivers and allow clients to join a multicast group

Protocol Independent Multicast (PIM)

Routers multicast traffic between routers and forms a multicast distribution tree

PIM Dense Mose (PIM-DM)

Uses periodic flood and prune behavior to form optimal distribution tree

PIM Sparse Mode (PIM-SM)

Uses a shared distribution tree and creates an optimal distribution tree through shortest path tree (SPT) switchover

Generic Routing Encapsulation (GRE)

Tunneling protocol used to encapsulate a wide variety of network layer protocol inside virtual point-to-point links over an Internet Protocol network