Terminology 2. Flashcards by Stephen Lawson

What are the two parts of a MAC address?

OUI - Organisationally Unique Identifier
Vendor assigned

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What is bit 47 of a MAC address?

I/G address bit (Individual/Group).
If 0, address is unicast address, if 1 it is a multicast/broadcast address
LSB of first octet

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What is bit 46 of a MAC address?

L/G address bit (Local/Global). Is the address is a burned-in address (BIA), or changed locally.
When set to 1, the address only has to be unique to the local network.
2nd LSB of first octet

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What is the structure of an Ethernet_II frame?

Preamble - 7 octets
SOF - 1 octet
Destination - 6 octets
Source - 6 octets
Type - 2 octets *
Data and Padding - 46 - 1500 octets
FCS - 4 octets

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What is the structure of an 802.3_Ethernet frame?

Preamble - 7 octets
SOF - 1 octet
Destination - 6 octets
Source - 6 octets
Length - 2 octets *
Data and Padding - 46 - 1500 octets
FCS - 4 octets

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What is encapsulating a frame with a different type of frame called?

Tunnelling

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In an ethernet frame, what is the preamble comprised of?

7 octets of an alternating 10101010 pattern

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In an ethernet frame, what is the SOF

Start of frame or synch. The SOF is 10101011, where the last pair of 1’s allows the receiver to predict the beginning of a frame.

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802.3 ethernet can not identify the network layer protocol. What sort of protocol is required for it to be used?

A proprietary LAN protocol, such as IPX.

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What is the ethertype for IPv4?

0x0800

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What is the ethertype for ARP?

0x0806

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What is the ethertype for VLAN tagged?

0x8100

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What is the ethertype for IPv6?

0x86DD

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What are the original IEEE 802.3 standards? (3)

10Base2 (thinnet)
10Base5 (thicknet)
10BaseT

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What is the access method defined in 802.3? And what is its limitation?

AUI (Attachment Unit Interface), which only allows one bit at a time transmission.

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802.3u (fast ethernet) introduced a new interface, what was it, how many bits at a time does it support?

MII (Media Independent Interface) - uses a nibble (4 bits at a time)

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Gigabit ethernet introduced a variation on the MII, what was it, how many bits at a time does it support?

GMII (Gigabit Media Independant Interface) - transmits 8 bits at a time.

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CWDM?

Coarse Wavelength Division Multiplexing
18 channels over a single fibre

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What are two common wavelengths for CWDM?

1310nm and 1550nm

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How many channels does CWDM allow for?

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DWDM

Dense Wavelength Division Multiplexing
80+ channels

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What is the maximum distance of CWDM?

70km

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How many channels does DWDM support?

80+

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What is the max speed DWDM supports?

400 Gbps per channel

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How far apart are CWDM channels?

20nm

How far apart are DWDM channels

0.8nm

What are the two LEDs typically found on a NIC called?

1. The link light - usually green, indicates that an ethernet connection has been established. 2. The activity LED - flickers to indicate activity. Other LEDs may indicate the speed of the connection.

A NIC is a layer _____ device.

A Hub is a layer ____ device.

What is the primary function of a Bridge?

To break up collision domains.

A Bridge is a layer ___ device.

What are the 3 significant differences between a switch and a hub?

1. A switch recognises frames 2. A switch pays attention to the source and destination MAC addresses 3. A switch makes each port a unique collision domain

A switch is a layer ____ device

A router is a layer ____ device

The term multi-layer switch refers to a ________.

router

What are the tree zones a triple homed router defines?

1. External (untrusted) 2. Internal (trusted) 3. DMZ or Screened subnet (trusted)

HIDS

Host-based Intrusion Detection System (runs on one computer)

PIDS

Protocol-based Intrusion Detection System (monitors traffic for one protocol on one server)

APIDS

Application Protocol-Based IDS (monitor for a group of servers running the same application)

How many collision domains does an AP create?

When using a WiFi range extender, what is the desirable overlap of the coverage areas of the AP and the extender?

15%

WLC

Wireless LAN Controller

What device can send incoming packets to multiple machines hidden behind one ip address?

Load balancer

CSMA/CA and CSMA/CD are examples of what?

Contention methods.

What does a "helper IP address" do?

It allows a router to forward a DHCP broadcast by forwarding it as a unicast address to the DHCP server.

What do "scope options" provide?

IP configuration for hosts on a specific subnet

What is the name of the process of forwarding a DHCP request to another LAN?

DHCP Relay

IPAM

IP Address Management - integrate with DHCP and DNS to help plan, track and manage IP addresses.

DNS A record

Address record, returns IPv4 address of domain

DNS AAAA record

Quad A record - returns IPv6 address

TXT (SPF) record

List of authorised hostname/IP addresses that can originate from a specific domain name

TXT (DKIM) record

Domain Keys Identified Mail - authentication of mail to prevent spam

SRV record

Service record, specifies port number as well as IP address

CAA record

Certificate Authority Authorisation - specifies authorised certificate authorities

CNAME record

Canonical name - alias one domain name to another

SOA record

Start of Authority - administrative information about a domain

PTR record

Pointer record for reverse DNS lookup

MX record

Mail Exchange record, how email should be routed

NS record

Name Service - authoritative DNS server for the domain

What is a recursive DNS lookup?

One DNS server will query other DNS servers rather than getting the client to perform all the operations

What is an Iterative lookup?

The client communicates with multiple DNS servers during the lookup process.

Dynamic DNS

Hosts register their their names with the DNS server as they receive their IP configuration from the DHCP server

External DNS

DNS server in the DMZ

Internal DNS

DNS server in the intranet

A proxy server is a layer _____ device

What does a Web Proxy Server do?

Creates a cache of web sites, including possible user data

What does a Caching Proxy Server do?

Keeps local copies of the resources requested often

A modem is a layer _____ device

What does a packet shaper do?

Increases bandwidth for some kinds of packets by delaying other kinds.

VPN Concentrator

(VPN headend) Hardware device that accepts multiple VPN connections

NFGW

Next-generation Firewall - layer 7 firewall

UTM

Unified Threat Management

DOCSIS

Data Over Cable Service Interface Specifications

PTZ

Pan/Tilt/Zoom - surveillance cameras

ASIC

Application-Specific Integrated Circuit

What is the DoD Model another name for?

TCP/IP Model

What are the four layers of the DoD Model?

Process/Application Layer Host-to-Host Layer Internet Layer Network Access Layer

What are two things the Process/Application layer defines?

Protocols for node to node communications. User-interface specifications

What OSI layer(s) does the Process/Application Layer correspond to?

Application, presentation and session

What OSI layer(s) does the Host-to-Host Layer correspond to?

Transport

What OSI layer(s) does the Internet Layer correspond to?

Network

What OSI layer(s) does the Network Access Layer correspond to?

Data Link, Physical

WINS

Windows Internet Naming Service

APIPA

Automatic Private IP Addressing

What is the APIPA range?

169.254.0.1 - 169.254.255.254

How long is a TCP header without options? With options?

20 bytes, Up to 60 bytes

Fields in a TCP Header? (in bytes)

Source port (2) Destination port (2) Sequence number (4) Acknowledgement number (4) Header Length (1) Reserved (1.5 (6 bits)) Code bits (1.5(6 bits)) Window (2) Checksum (20) ___ Options (0 or 4)

The 1 byte TCP header length contains the length of the header in ___ ____ _______

32 bit words

What are the code bits for in a TCP header?

To control functions used to set up and terminate a session. This is where the flags, such as SYN etc, are

The 2 byteTCP window field holds the window size in ______

octets

What determines whether the urgent field is valid in a TCP header

The urgent pointer in the code bits

What does the urgent field in a TCP header contain

The offset from the current sequence number to where non-urgent data begins

How many bytes is a UDP header?

What are the fields in a UDP header ?(in bytes)

Source port (2) Destination port (2) Length (2) Checksum (2)

What are the Fields in an IP header? (in bits)

1. Version (4) 2. Header length (4) 3. Priority and type of service (8) 4. Total Length (16) 5. Identification (16) 6. Flags (3) 7. Fragmented Offset (13) 8. Time to live (8) 9. Protocol (8) 10. Header Checksum (16) 11. Source IP Address (32) 12. Destination IP Address (32) 13. Options (0 or 32 if any)

What is the Identification field in an IP header used for?

To differentiate fragmented packets from different datagrams

What is the Flags field in an IP header used for?

Specifies whether fragmentation should occur

In an IP header, what is the protocol number for ICMP

In an IP header, what is the protocol number for IP (in IP tunnelling)

Terminology 2. Flashcards

(99 cards)