Secure Networking Technologies

Front 1

Define Cut-Through Switching, and when it is ideally used?

Back 1

Starts forwarding a frame before the whole frame has been received, normally as soon as the destination address has been processed.

Ideally used when transmission delay is needed to be avoided and no priority is needed.

Front 2

Define store-and-forward switching, and when it is ideally used?

Back 2

Waits until the entire frame has arrived, checks destination and source, and CRC, if no errors then forwards the packet.

Ideal when bad frames need to be discard, and prioritising of certain protocols.

Front 3

Define Symmetric switching

Back 3

Provides switched connection between all ports with the same bandwidth.

Front 4

Define Asymmetric switching

Back 4

Enables more bandwidth to be dedicated to one switch port to prevent bottle neck.

Front 5

Give 3 reasons why a single subnet is easier to manage

Back 5

Only need to configure one DHCP scope

Some older protocols require all devices to be in a single subnet

Only need to configure one firewall, especially when basing it on IP address rules.

Front 6

Are broadcasts transmitted across VLANs on the same switch?

Back 6

No, they still behave if they are physically seperated.

Front 7

How many VLANs can one physical switch be divided into?

Back 7

VLAN ID field is 12 bits, giving a maximum of 4096 VLANs.

Front 8

How VLANs can an access port belong too?

Back 8

Only one

Front 9

How many bytes is a Trunk Tag?

Back 9

Four

Front 10

What does Trunking do to a frame?

Back 10

Adds a tag that contains the VLAN ID, and is used to prioritise frames.

Front 11

When a single NIC has multiple subinterfaces configured using 802.1Q VLAN tags, does it require the VLANS be on the same IP Subnet?

Back 11

The VLANs can be on multiple different IP Subnets.

Front 12

What happens to untagged frames that are sent out on a trunk port and received on a trunk link?

Back 12

They are assumed to belong to the Native VLAN.

Front 13

What is the default Native VLAN on a trunk port?

Back 13

VLAN 1

Front 14

What happens when 2 Cisco devices are connected and do not share the same native VLAN?

Back 14

"Native VLAN Mismatch" warning will show.

Front 15

Do you always a Crossover Cable to connect two switches? Explain your answer.

Back 15

No, modern equipment can use Auto Sensing to work with crossover or straight-through cables.

Front 16

How is a broadcast address at the physical layer written?

Back 16

All F's (FF:FF:FF:FF:FF:FF)

Front 17

What is latency a measure of?

Back 17

Latency is the measure of delay that information is subject to when transmitted.

Front 18

What do you use to connect VLANs?

Back 18

Routers

Front 19

Define: Half-duplex mode

Back 19

A port will either transmit or receive data cannot do both at the same time.

Front 20

Define: Full-duplex mode

Back 20

A port can transmit and receive data at the same time.

Front 21

How many broadcast and collision domains does a hub have? Explain your answer.

Back 21

1 Broadcast and 1 Collision domain.

Packets are broadcast to all ports to hit the right destination, so all other ports cannot send at the same time or collision will occur.

Front 22

How may broadcast and collision domains does a switch have? Explain your answer.

Back 22

1 Collision domain for each port. 1 Broadcast domain per VLAN.

If a switch receives a packet for MAC address not its ARP table, it will broadcast to all ports in the VLAN.

Front 23

How many broadcast and collision domains does a router have?

Back 23

1 Broadcast domain and 1 collision domain per port.

Front 24

What is fast forward switching?

Back 24

Packet if forwarded as soon as the destination MAC is known.

Front 25

What is fragment free switching?

Back 25

Waits until the minimum frame of 64 bytes has been received.

Front 26

How many VLANs can a Cisco ACCESS switchport be assigned to?

Back 26

Only assigned to 1 VLAN, but can by dynamically assigned.

Front 27

How many ports are needed to route all VLANs on a switch to the internet?

Back 27

One port needed, 802.1Q trunking can be used, traffic from all VLANs can be tagged with a VLAN ID.

Front 28

When two switches are connected together without VLANs, what two things will happen?

Back 28

Broadcasts will be forwarded between the switches.

MAC addresses for all devices on one switch will appear in the MAC table of the other switch.

Front 29

Which layer does a Hub, a Switch and a Router operate on?

Back 29

Hub - Layer 1 (Physical layer)

Switch - Layer 2 ( Data link layer)

Router - Layer 3 ( Network Layer)

Front 30

True or False: Microsoft's DHCP service can be clustered?

Back 30

True

Front 31

Can two DHCP servers offering the same range of IP addresses check IP's have been leased already?

Back 31

They normally do not check so clashes can happen.

Front 32

How does Static NAT work?

Back 32

Maps a private IP address to a static public IP address without referencing ports.

Front 33

How does Dynamic NAT work?

Back 33

Private IP addresses are mapped to a pool of public IP addresses. Helps mask the internal configuration of a private network.

Front 34

How does RIP routing work?

Back 34

Uses hop count as a routing metric, the maximum hops allowed is 15.

Front 35

How does Link-State routing work?

Back 35

Every router will independently calculate the best next logical path from itself, to every other possible destination on the network. Sends routing information to other routers as soon as change happens. Requires more resources and overhead.

Front 36

How does Distance-Vector routing work? Name three types.

Back 36

Each router shares its routing table and topology changes with its neighbours periodically. Requires less resources and overhead.

RIP, IGRP and Babel

Front 37

What does OSPF stand for, its type of routing protocol and how does it work?

Back 37

Open Shortest Path First

Type of Link-state protocol

Gathers information from other routers, constructs a topology of the network and passes it to the Internet layer.

Front 38

Which type of routing protocol is effected by the count-to-infinity problem?

Back 38

Distance Vector protocols.

Front 39

Define "Administrative distance"

Back 39

Which protocol to use if more than one protocol has provided route information. The reliability of the source of information about the route.

Front 40

Define Iterative DNS query

Back 40

Returns a referral to another DNS server.

Front 41

Define Authoritative DNS query

Back 41

The answer is retrieved directly from the DNS database

Front 42

Define DNS zone

Back 42

Refers to an administrative space within the global Domain Name System. Each zone represents a boundary of authority which is managed by an legal entity, such as a country code.

Front 43

What are entries in a DNS database known as?

Back 43

Resource Records

Front 44

What does CHAP (authentication) stand for? What does it protect against and how does it work?

Back 44

Challenge Handshake Authentication Protocol

Protects against replay attacks

Sends a challenge message, peer responds with a calculated hash, CHAP checks hash. At random intervals this is repeated.

Front 45

What kind of authentication is Keberos

Back 45

Certificate-based

Front 46

What does NTLM stand for, and what does it provide for authentication security?

Back 46

Adds unique information to the attempt, checks if the Nonce is its own, which helps prevent reflection attacks.

Front 47

How does Microsoft Active Directory use authentication?

Back 47

All machines in a domain trust each other as hold tickets signed by Domain Controllers, which are issued using Kerberos.

Front 48

How does double tagging work?

Back 48

Attacker adds trunk tags, first tag gets removed, when frame reaches switch, second tag is seen and forwards to the switch.

Front 49

How to mitigate double tagging?

Back 49

Keep the native VLAN of the trunk ports different. Authenticate trunks.

Front 50

What does OCSP and CRL stand for, and what are they?

Back 50

Online Certificate Status Protocol

Certificate Revocation List

OSCP is a dynamic check, CRL is just a list of revoked certificates.

Front 51

What happens when a station detect a collision?

Back 51

Ceases transmission, waits a random amount of time, then attempts to transmit again.

Front 52

What is a replay attack?

Back 52

An attacker snoops the password/hash and the attacker sends the hash providing access to the victims session.