Introduction to Routing Flashcards
What is the primary function of a router?
To route traffic between different networks.
How do routers differ from switches?
Routers (Layer 3) separate broadcast domains, while switches (Layer 2) maintain a single broadcast domain.
What are the three primary functions of routers?
- Route traffic between subnets.
- Route traffic between an internal and external network.
- Route traffic between two external networks.
What happens when a packet needs to leave a LAN?
The packet is forwarded to the default gateway (a router).
What is a Layer 3 switch?
A device that performs both Layer 2 switching and Layer 3 routing.
How is a Layer 3 switch treated in an exam?
If performing routing, it is considered a router. If referred to only as a switch, it is considered a Layer 2 device.
Where are Layer 3 switches commonly used?
Small and medium businesses (SMBs) due to their dual functionality.
What does a routing table contain?
- A prefix (network address). 2. A destination network and next-hop router. 3. The exit interface. 4. The cost of the route.
What are the three sources of routing information?
- Directly connected routes. 2. Static routes (manually configured). 3. Dynamic routes (learned via protocols).
What is CIDR notation used for in routing?
A higher CIDR notation (e.g., /24) shows ip address ranges and network size for routing
What are the two major categories of routing protocols?
- Interior Gateway Protocols (IGPs) – Used within an autonomous system.
- Exterior Gateway Protocols (EGPs) – Used between autonomous systems.
What is the difference between Distance Vector and Link State protocols?
Distance Vector uses hop count (e.g., RIP). Link State uses link cost and bandwidth (e.g., OSPF).
What is the purpose of BGP?
BGP is an EGP used to route between autonomous systems, making it the backbone of the Internet.
What is Administrative Distance (AD)?
A measure of trustworthiness for a route, with lower AD values being more trusted.
Which route type has the lowest Administrative Distance (AD)?
Directly connected routes (AD = 0).
What metric does RIP use for route selection?
Hop count (fewer hops = better route).
How does OSPF determine the best route?
By using cost based on bandwidth.
Why is NAT used in networking?
To conserve IPv4 addresses by allowing multiple private devices to share a limited number of public IPs.
What are the three types of NAT?
- Dynamic NAT (DNAT) – Assigns public IPs from a pool.
- Static NAT (SNAT) – Maps a private IP to a fixed public IP.
- Port Address Translation (PAT) – Multiple private IPs share a single public IP using ports.
Which NAT method is most commonly used today?
Port Address Translation (PAT).
What is the purpose of Routing Redundancy Protocols?
To ensure network reliability by automatically switching to a backup router if the primary router fails.
What are the three main First Hop Redundancy Protocols (FHRP)?
- HSRP (Cisco Proprietary) – Active-standby. 2. VRRP (Open Standard) – Vendor-neutral. 3. GLBP (Cisco Proprietary) – Supports load balancing.
What is the difference between HSRP and GLBP?
HSRP uses an active-standby model, while GLBP supports load balancing.
What is the main advantage of Multicast Routing?
It reduces network congestion by sending data only to devices that request it.
What are the two primary multicast protocols?
- IGMP – Manages host group membership. 2. PIM – Routes multicast traffic between routers.
What are the two PIM modes?
- PIM Dense Mode (PIM-DM) – Floods traffic to all routers first, then prunes unnecessary paths. 2. PIM Sparse Mode (PIM-SM) – Builds multicast trees only where needed.
What is GRE used for?
To encapsulate different network layer protocols inside a virtual tunnel.
How does GRE differ from VPN?
GRE supports multiple network protocols but lacks encryption, while VPN (IPSec) encrypts traffic.
How can GRE be secured?
By combining GRE with IPSec for encryption.
Which protocol is used for routing on the internet?
Border Gateway Protocol (BGP).
What is split horizon?
A technique that prevents routing loops by stopping routers from advertising a route back through the interface it was learned from.
Which protocol uses cost as a routing metric?
OSPF.
What is a static route?
A manually configured route used when no dynamic routing protocol is needed.
What is the main disadvantage of RIP?
Slow convergence and a maximum hop count of 15, making it unsuitable for large networks.
What does EIGRP use as its primary metric?
Bandwidth and delay.
What does an ARP request do?
Resolves an IP address to a MAC address within a LAN.
What is the main function of a default gateway?
To allow traffic to leave a local network and reach other networks.
What is the role of the MAC address in networking?
It is used for Layer 2 communication within a local network.
