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Network+ > Lesson 16: Comparing WAN Links and Remote Access Methods > Flashcards

Lesson 16: Comparing WAN Links and Remote Access Methods Flashcards

1
Q

What is the function of a modem?

A

A modem performs modulation of outgoing signals and demodulation of incoming data, working only at the physical layer of the OSI model

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2
Q

Define modulation

A

Process of converting data into electrical signals optimized for transmission

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3
Q

Define demarcation point

A

Location that represents the end of the ISPs network and therefore their responsibility for maintaining it; The demarc point is usually at the Minimum Point of Entry (MPOE)

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4
Q

Define DSL (Digital Subscriber Line)

A

ISP technology to implement broadband Internet access for subscribers by transferring data over voice-grade telephone lines

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5
Q

What are the types of DSL (Digital Subscriber Line)

A
  1. Symmetrical DSL (SDSL)
  2. Asymmetrical DSL (ADSL)
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6
Q

Define Symmetrical DSL (SDSL)

A

Provides the same downlink and uplink bandwidth; typically provided as business packages, rather than to residential customers

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7
Q

Define Asymmetrical DSL (ADSL)

A

Consumer version of DSL that provides a fast downlink but a slow uplink, with the latest (ADSL2+) offering downlink rates up to about 24 Mbps and uplink rates up to 3.3 Mbps

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8
Q

What are the benefits of satellite?

A

Larger coverage areas, especially to rural areas

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9
Q

What type of cable can be used to connect a CSU/DSU to a smartjack, assuming a maximum link distance of 1m (3 feet)?

A

straight-through RJ-45

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10
Q

Define remote access

A

the user’s device does not make a direct cabled or wireless connection to the network. The connection occurs over or through an intermediate network, usually a public WAN

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11
Q

What are useful policies to consider when implementing remote access?

A
  • Restricting access to defined users or groups.
  • Restricting access to defined times of day or particular days of the week.
  • Restricting privileges on the local network
  • Logging and auditing access logons and attempted logons.
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12
Q

Define a VPN (Virtual Private Network)

A

Secure tunnel created between two endpoints connected via the internet

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13
Q

Define Point-to-Point protocol (PPP) for VPN

A

A layer 2 tunneling protocol encapsulated in TCP/IP that creates a direct link between two points

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14
Q

Define Generic Routing Encapsulation (GRE)

A

Tunneling protocol in which an unsupported data type (layer 3 protocol) is encapsulated in a GRE packet, the GRE packet is encapsulated in layer 2 packet before being forwarded to a router

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15
Q

Define IP Security (IPSec)

A

Network protocol suite used to secure IPv4 and/or IPv6 communications through authentication and encryption as the data travels across the network or the Internet

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16
Q

Define TLS (Transport Layer Security) in the network layer

A

Transport Layer Security (TLS) over TCP or datagram TLS (DTLS) over UDP can be used to encapsulate frames or IP packets

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17
Q

What is a drawback from using TLS at the network layer?

A

TLS already operates at the session layer, the headers from the inner and outer packets add up to a significant overhead

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18
Q

Define the client-to-site VPN topology

A

the VPN client connects over the public network to a VPN gateway (a VPN-enabled router) positioned on the edge of the local network (typically the VPN access server will be in a screened subnet); basic model for home/field workers

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19
Q

What are the two types of client connections formed once a client is connected to a client-to-site VPN?

A
  1. Split tunnel
  2. Full tunnel
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20
Q

Define a split tunnel VPN connection

A

VPN configuration where only traffic for the private network is routed via the VPN gateway

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21
Q

Define a full tunnel VPNconnection

A

VPN configuration where all traffic is routed via the VPN gateway

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22
Q

Between split tunnel and full tunnel VPN connections, which is better for security?

A

Full tunnel offers better security, but the network address translations and DNS operations required may cause problems with some websites, especially cloud services. It also means more data is channeled over the link and the connection can exhibit higher latency

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23
Q

Define a clientless VPN

A

Using features of HTML5 to implement remote desktop/VPN connections via browser software (clientless) - like citrix

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24
Q

How do clientless VPNs function?

A

Using a protocol called websockets, it enables server and client to communicate biderictionally without requiring separate HTTP requests

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25
Q

Define a site-to-site VPN topology

A

Configured to connect two or more private networks automatically without intervention from clients through the edge router

26
Q

How can an ISP create site-to-site VPNs?

A

A WAN service provider can implement VPNs via its network by using VLAN-like technology to isolate a customer’s data from other traffic.

27
Q

Define a screened subnet and its purpose

A

An edge subnet containing a VPN gateway and an edge router to screen and isolate traffic from an internal network with its own firewall

28
Q

What is the purpose of a VPN in a local network?

A

To secure communications between departments

29
Q

Define a hub and spoke VPN topology

A

A site-to-site VPN that involves more than two sites connects the remote sites (or spokes) to a headquarters site (hub) by using static tunnels configured between the hub and each spoke

30
Q

Define a VPN headend

A

Hub of the hub and spoke topology that incorporates advanced encryption and authentication methods in order to handle a large number of VPN tunnels

31
Q

What is the best method of installation for VPN headends

A

Powerful routers installed in groups for load balancing and fault tolerance, referred to as branch office routers

32
Q

Define a dynamic multipoint VPN (DMVPN) and its purpose

A

Software-based mechanism that creates a mesh topology between multiple remote sites and allows VPNs to be built and deleted dynamically between two sites, effectively setting up direct VPNs, rather than the remote sites having to route traffic via the hub.

33
Q

How are dynamic multipoint VPNs (DMVPN) configured?

A

Each remote site’s router is still connected to the hub router using an IPSec tunnel

34
Q

How does a dynamic multipoint VPN (DMVPN) function?

A

If two remote sites (spokes) wish to communicate with one another, the spoke instigating the link informs the hub. The hub will provide the connection details for the other spoke facilitating a dynamic IPSec tunnel to be created directly between the two spokes.

35
Q

What routing and network protocols are used in dynamic multipoint VPN (DMVPN) configurations?

A

Next Hop Router Protocol (NHRP) to identify destination addresses and the GRE tunneling

36
Q

What is the purpose of GRE in dynamic multipoint VPN (DMVPN) configurations?

A

GRE encapsulates the encrypted IPSec packets

37
Q

How does traffic flow between two spokes in a dynamic multipoint VPN (DMVPN) configuration?

A

The two remote sites use the physical communications links between the two locations but all traffic flows over the temporary, encrypted VPN tunnel setup between them.

38
Q

How does IPSec function at the host/client level?

A

Each host that uses IPSec must be assigned a policy, hosts must be able to match at least one matching security method for a connection to be established

39
Q

What are the two sub-protocols used in IPSec?

A
  1. Authentication Header (AH)
  2. Encapsulating Security Payload (ESP)
40
Q

How does IPSec operate with the Authentication Header (AH) sub-protocol when initiating a connection?

A

Performs a cryptographic hash on the whole packet, including the IP header, plus a shared secret key (known only to the communicating hosts), and adds this secret in its header as an Integrity Check Value (ICV)

41
Q

What is the function of the Authentication Header sub-protocol?

A

provides authentication for the origin of transmitted data as well as integrity and protection against replay attacks

42
Q

How does IPSec operate with the Authentication Header (AH) sub-protocol when receiving a connection?

A

The recipient performs the same function on the packet and key and should derive the same value to confirm that the packet has not been modified

43
Q

What is the drawback to the Authentication Header (AH) sub-protocol?

A

The payload is not encrypted so this protocol does not provide confidentiality. Also, the inclusion of IP header fields in the ICV means that the check will fail across NAT gateways, where the IP address is rewritten

44
Q

What are the advantages of Encapsulating Security Payload (ESP) sub-protocol over Authentication Header (AH) sub-protocol?

A
  1. Provides confidentiality and/or authentication and integrity
  2. Excludes the IP header when calculating the ICV allowing the packet to transverse gateways
45
Q

How does IPSec differ between IPv4 and IPv6

A

IPSec makes use of extension headers in IPv6 while in IPv4, ESP and AH are allocated new IP protocol numbers (50 and 51), and either modify the original IP header or encapsulate the original packet, depending on whether transport or tunnel mode is used

46
Q

What does IPSec depend on for encryption and hashing?

A

IPSec depends on a shared secret between hosts that is used to authenticate communications between the two hosts

47
Q

Define a Security Association (SA)

A

A Security Association (SA) establishes that two hosts trust one another (authenticate) and agree secure protocols and cipher suites to use to exchange data

48
Q

What is the purpose of the Internet Key Exchange (IKE) protocol?

A

Creates Security Associations (SAs) between hosts and handles authentication and key exchange.

49
Q

What two modes can IPSec be utilized in?

A
  1. Transport mode
  2. Tunnel mode
50
Q

What is the purpose of IPSec in transport mode?

A

Used to secure communications between hosts on a private network.

51
Q

How does IPSec with Encapsulating Security Payload (ESP) sub-protocol function in transport mode?

A

When ESP is applied in transport mode, the IP header for each packet is not encrypted, just the payload data.

52
Q

How does IPSec with Authentication Header (AH) sub-protocol function in transport mode?

A

If AH is used in transport mode, it can provide integrity for the IP header.

53
Q

What is the purpose of IPSec in tunnel mode?

A

Used for communications between VPN gateways across an unsecure network (creating a VPN). This is also referred to as a router implementation.

54
Q

How does IPSec with Encapsulating Security Payload (ESP) sub-protocol function in tunnel mode?

A

With ESP, the whole IP packet (header and payload) is encrypted and encapsulated as a datagram with a new IP header

55
Q

How does IPSec with Authentication Header (AH) sub-protocol function in tunnel mode?

A

AH has no real use case in tunnel mode, as confidentiality will usually be required

56
Q

What are different types of interfaces used to connect to a managed appliance?

A
  1. Console port
  2. Aux port
    3.Management port
57
Q

How does a console port/interface function?

A

Requires connecting a device running terminal emulator software (a laptop, for instance) to the device via a separate physical interface using a special console (or rollover) cable. The terminal emulator can then be used to start a command line interface (CLI)

58
Q

How does a management port/interface function?

A

Configuring a virtual network interface and IP address on the device to use for management functions. The port must be enabled for this function. Using Telnet (unsecure) or Secure Shell (SSH) to connect to a CLI remotely over the management interface in this way is referred to as a virtual terminal.

59
Q

What is in-band management?

A

An in-band management link is one that shares traffic with other communications on the “production” network.

60
Q

What is out-of-band management?

A

Accessing the administrative interface of a network appliance using a separate network from the usual data network; console port or having management port on separate physical network

61
Q

What type of client-to-site VPN ensures that any traffic from the remote node can be monitored from the corporate network while the machine is joined to the VPN?

A

Full tunnel.

62
Q
A

Network+ (19 decks)

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