Switch features

Question 1

Switches are often described in two planes. Control plane and Data plane. What are these both responsible for?

Answer 1

Control - Managed switch hardware and software that enables interfacing and management of a switch
Data - The “Dumb” part of a switch that does the natural job of relaying data.

Question 2

What are three methods of interfacing with a switch?

Answer 2

1) Web interface
2)Console port
3)Putty via a networked PC

Question 3

True or false: You need to use putty / some terminal software even when using a console port to interface with a switch

Answer 3

True

Question 4

What is In-band management and Out-of-band management?

Answer 4

In-band management: Connecting and managing a switch over the same network it’s servicing - Often seen as a security risk
Out-of-band: Connecting to and managing a switch through means outside of the network the switch is serving. Ex: Having a private network just for monitoring you use to connect to the switch.

Question 5

What is a management port?

Answer 5

This is a security feature with which a switch will only allow interfacing on a single, manually allocated port.

Question 6

What are three switch commands?

Answer 6

show config
show interface
show route

Question 7

What is flow control?

Answer 7

Flow control is a method by which slower computers can send a “pause frame” to switches to tell them to halt their stream of data so the PC can ‘catch its breath.’

Question 8

What are jumbo frames?

Answer 8

Allow the exceeding of the MTU size of 1500 bytes of payload per frame. This works well internally, but out on the WAN is little support for this and it will inevitably cause issues for you.

Question 9

What is port security

Answer 9

A switch will only work with a specific MAC address provided to it. Security feature.

Question 10

What is sticky MAC

Answer 10

Dynamic learning and storage of MAC addresses for port security. It memorizes and stores MAC addresses it knows to be safe and blocks unauthorized ones.

Question 11

Can two vlans communicate through the same switch they were made on?

Answer 11

False. Unless it is a L3 multi-layer switch, the L2 switch will need a router to perform the inter-vlan routing.

Question 12

Switches, when dealing with simple point to point connections, allow broadcast frames to pass through. Is this also true of VLANS?

Answer 12

Broadcasts will not pass between VLANS

Question 13

What is switch trunking?

Answer 13

Enables communication between the vlans of two separate switches

Question 14

What is 802.1Q?

Answer 14

Switch trunking. This enables trunking between different hardware brands.

Question 15

What is a static vlan?

Answer 15

A static VLAN is a group of ports designated by the switch as belonging to the same broadcast domain. Your bog standard vlan.

Question 16

802.1Q is port trunking. It enables communication between different VLANS. But how does it achieve this?

Answer 16

It uses a “tag” added to the frames sent to identify where the frame should be headed.
If the frame is for someone on the same switch, it will simply send it through as usual.
If the frame is the same VLAN but not connected to the original switch directly, it will send it through the trunking port without a tag.
If the frame is for a different VLAN entirely, it will tag it for said VLAN and send it on its way.

Question 17

What is a native vlan?

Answer 17

Backwards compatibility with hardware that doesn’t support the tagging system.

Question 18

What is VTP?

Answer 18

Vlan trunking protocol is a cisco proprietary protocol that enables management of multiple cisco switches. It automatically updates other switches with new vlan information if set to do so. Saving you from having to manually alter every switch with new info.

Question 19

What is inter-vlan routing?

Answer 19

VLANs cannot exchange information.
Like real networks, it must be routed.

Question 20

What is sub-interfacing

Answer 20

Using one physical port and logically dividing it into multiple logical connections

Routers can use just one port to support multiple vlan connectors. This is done through sub-interfacing, the act of logically splitting a single port, usually used for just one connection into multiple “channels” so that it may carry multiple sets of data at once for different vlans.

Question 21

What is the purpose of a DHCP relay

Answer 21

To allow DHCP DORA (Discover, Offer, Response, Accept(?) packets through a router that would otherwise block them.

Question 22

What is a private VLAN port

Answer 22

A VLAN port that cannot communicate with any other port on the switch. A segregated network.

Question 23

True or false: Private vlan ports can only interact with the trunk uplink port

Answer 23

True

Question 24

The majority of the time, if you set up a new VLAN and someone can’t access resources, what is the likely issue?

Answer 24

Wrongly assigned VLAN ports.

Question 25

What is a switch port and router port?

Answer 25

Switch port forwards based on mac, router port forwards based on IP.

Question 26

What is load balancing?

Answer 26

The act of evenly spreading out incoming requests across servers as to ensure one server doesn’t take all the burden and become overloaded.

Question 27

How does DNS load balancing work?

Answer 27

You make A records for your servers and assign them all the same FQDN.
You then tell your server to “round robin” or “cycle” through them.

This makes the DNS server cycle through the servers it sends requests to as compared to sending all data to just one.

Question 28

What is BIND DNS?

Answer 28

Assigns servers requests based on their workload. An alternative to round robin load balancing.

Question 29

What is a content switch?

Answer 29

A specialised layer 7 switch that reduces workload on servers by doing some of the work themselves (In the case of a HTTP content switch, they would send cookies and deal with TLS related things) and also performing load balancing as they do so.

Question 30

What is bandwidth/traffic shaping

Answer 30

Controlling the flow of packets within/without the network. You can also assign minimum bandwidth to a specified machine.

Question 31

What is port bonding, link aggregation, NIC bonding, port aggregation, etc?

Answer 31

Logically dedicating two ports on a switch to the same connection. This increases bandwidth.

Question 32

What’s the difference between IPS and IDS?

Answer 32

IPS acts like a firewall and guards from external threads. IDS is usually inside the network and detects issues from within that a firewall may have missed. IDS also deals with things such as virus USB sticks being plugged into the network.

Question 33

Does an IDS sit within or without the flow of network traffic

Answer 33

Without.
IDS takes a copy of everything that is sent over the network (via port mirroring*) and scans it for threats.
The IDS cannot take action itself, but can employ other security programs to tackle a bad situation

*Port mirroring refers to when data comes in on one port, and is then replicated out on another for the sake of maintenance and data collection.