Routing Flashcards
What level do routers work at?
Layer 3
On a router, what does a console port do?
Used to plug in laptops and directly interact with the router for maintenance
Switches that can also route are called _______
Multi-layer switches MLS
What’s the first thing a router does when it gets a frame?
Strips away the MAC data to replace it
What 5 things will you commonly see on a routing table?
Destination - The IP of the connected node
Gateway - The gateway of the router. Takes any packets not able to be locally sourced.
Genmask - Another name for subnet
Type - Whether the call is to the WAN port or on LAN ports
Metric - Priority
On a routing table, what is a flag?
A letter used to indicate certain properties of a connection.
Ex: C - Connected
H - Destination is a host
True or false: Routers will send the packet to the first matching address on the routing table they find
False. They will scan the whole routing table before sending
What does a 0.0.0.0 address mean on a routing table
The IP address doesn’t matter
What would be the result of
DEST GATEWAY GENMASK TYPE
192.168.0.3 * 255.255.255.0 LAN
ARP out to the LAN for the MAC address, then send the packet to that recipient.
What would be the result of
DEST GATEWAY GENMASK TYPE
192.168.0.0 * 255.255.255.0 WAN
ARP out to WAN port
What is the win command for seeing your routing table
route print
What is dynamic routing protocol
Routers sharing information to keep their routing tables optimal
What is port address translation?
When a NAT device maps internal addresses and ports to routable ones, allowing private IPs to talk to external networks.
More info:
Priv IP computer sends a packet for an external network on 192.168.0.5:2000 > As this isn’t a routable IP, the NAT device substitutes the Priv IP and port for its own Routable ones. It then remembers the port it has used so it knows how to translate it back when the packet returns from the web.
What is port forwarding?
Enabling external, unsolicited connections via specific ports. It forwards the information to a specific computer listening on that port.
What is Pooled Nat?
Dynamic NAT. Using a pool of routable IP addresses amongst computers. Leasing them out as needed temporarily.
What’s the difference between PAT and Port forwarding?
PAT translates IP and ports for outgoing connecitons
Port forwarding forwards information on incoming connections into the network via ports.
What is SNAT?
Static NAT maps a single, routable address to a specified machine. This enables access externally to the PC or server.
What is Distance Vector
Something used by networking protocols that prioritize the hop count between source and destination to dictate the metrics of routing tables.
True or false x2
Distance Vector updates at 30s intervals (aside from RIPv2 which is 90)
Link state deletes all alternate paths to a single point from its routing table apart from the most efficient method
Both true
What is convergance/steady state
When routers have finished exchanging routing information and have optimal paths.
How many routers is it suggested you use with RIP, the distance vector protocol?
Less than 10 due to the 30s interval of information regarding routing tables can overload your network
What is an AS?
Autonomous Systems are owned by big name networks in each country and use a unified policy to communicate.
What is BGP and the two protocols it includes
Border gateway protocol defines how AS interact with other AS outside of the ones they own.
-Exterior and interior gateway protocol
What is the means by which AS identify themselves?
Using an Autonomous System Number (ANS)
True or false: BGP is NOT a hybrid protocol
False. Being a part of internal and external gateway protocol, it is a hybrid.
What is route aggregation
A method by which AS reduce the amount of entries needed on their routing tables. Instead of memorizing the many hundreds of ways to send a packet into one country, it will simply pick the highest quality one that can send the packet to the destination and erase the rest of the non-used connections from the table.
What is an edge router?
AS-to-AS connected routers that leave one network to contact another.
What is link state
Prioritizes bandwidth and speed to decide upon routing table metrics in comparison to Distance Vector’s hop count method
Also updates routing tables as changes are made rather than in 30s intervals and has near immediate convergance
When would an AS use Exterior Gateway protocol?
When it needs to contact an AS outside of its own network
How do Link-state Routers exchange information?
> Hello Packets
Routers form neighborship
Neighborship enables exchange of link state advertisement (LSA) packets that contain info
Is EIGRP Distance vector or Link state?
Neither. it’s a hybrid protocol that came out before OSPF but after RIP.
Using the 222 rule, name all the DV, LS and Hybrid protocols.
DV \_\_\_\_\_\_\_\_\_\_\_\_\_\_ RIP 1 RIP2 EIGRP \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ HYBRID \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ BGP EIGRP - Enhanced interior gateway protocol
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ LS \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ OSPF IS-IS
What is BGP
Border gateway protocol defines how Autonomous Systems edge routers interact with one another to exchange information.
What is route distribution
When a multi-lingual router (IE one that can do DV and LS) can inform multiple types of routers on the best paths to take.
A multi-lingual router has two different paths it can take. It bases this from being able to use RIP and OSPF. Using _________ the router decides to use the OSPF route.
Route preference/administrative distance
“Oi cunt, gimme the yost cable.” What is he saying?
Give me the Console/Rollover cable
What is a managed switch
An interfacable switch
How do you interface with a router/switch? Two steps.
1) Use a rollover cable
2) Use putty to sign in
3) do your shit
A technician just finished setting up his second router. His first is using RIP and, wanting some variety, has his second use OSPF. They do not interconnect. Why?
Dynamic routing protocols must be the same for the routers to communicate.
True or false: Dynamic routing protocols are tied to switch/router interfaces (the physical ports) and not the router/switch itself?
Twoo
What is a protocol data unit?
The data passed between layers of the OSI model. When the PDU reaches its maximum size, it is called a MTU.
What is the difference between tracert and pathping
Tracert - Used to diagnose faults or dead connections between the computer doing the tracert and a destination IP address
Pathping - Used to diagnose packet loss or connection issues between your computer and your router.
What is a router?
A. A piece of hardware that forwards packets based on IP address
B. A device that separates your computers from the Internet
C. A piece of hardware that distributes a single Internet connection to multiple computers
D. A synonym for a firewall
A. A piece of hardware that forwards packets based on IP address
What technology allows you to share a single public IP address with many computers? A. Static address translation B. Natural address translation C. Computed public address translation D. Port address translation
D. Port address translation
Which of the following is an EGP? A. BGP B. IGP C. EIGRP D. IS-IS
A. BGP
What is Area 0 called in OSPF? A. Local Area B. Primary Zone C. Trunk D. Backbone
D. Backbone
Which of the following is not a name for a serial cable that you use to configure a router? A. Console cable B. Yost cable C. Rollover cable D. Null modem cable
D. Null modem cable
When you are first setting up a new router, you should never plug it into an existing network.
A. True
B. False
A. True
Otherwise you may get a rogue dhcp server
The traceroute utility is useful for which purpose?
A. Configuring routers remotely
B. Showing the physical location of the route between you and the destination
C. Discovering information about the routers between you and the destination address
D. Fixing the computer’s local routing table
C. Discovering information about the routers between you and the destination address
What is port mirroring?
Sending a copy of data that comes in on a port to a specified other port. This can be used for monitoring purposes.
What is circuit switching
Circuit switching is a type of network configuration in which a physical path is obtained and dedicated to a single connection between two endpoints in the network for the duration of a dedicated connection.
A phone call would be an example of this.
An Ethernet switch table containing IP-to-MAC address mappings is known as: ARP table Routing table MAC address table DNS table
ARP table
What is Multiprotocol Label Switching
This is when connection paths are made based on labels instead of IP addresses. If you want a specific route to be taken to a destination, you can use this to ensure it happens.
Multiprotocol Label Switching is a routing technique in telecommunications networks that directs data from one node to the next based on labels rather than network addresses. Whereas network addresses identify endpoints the labels identify established paths between endpoints. MPLS can encapsulate packets of various network protocols, hence the multiprotocol component of the name. MPLS supports a range of access technologies, including T1/E1, ATM, Frame Relay, and DSL
What is LACP
Link Aggregation Control Protocol allows two switches / routers to use multiple ports and runs of their ethernet cables for just one set of data transfer to increase their bandwidth.
https://support.huawei.com/enterprise/en/doc/EDOC1100086560
What is IEEE 802.1X?
The use of a radius server to authenticate login credentials
What is DHCP Snooping
DHCP snooping is a layer two security function according to the OSI model. The function is installed in the switch that connects clients to the DHCP servers. In simple terms, it is a protocol that first checks all DHCP information that passes through the switch. Only approved packages from trusted servers are allowed through to clients.
https://www.ionos.com/digitalguide/server/security/dhcp-snooping/
