Cisco CCENT

Priv Exec Mode Symbol

# Can reload switch

MAC Address

(Media Access Control) 802.3 (Ethernet) defines the MAC sublayer of IEEE Ethernet

Symbol and level of Conf

(config) - change actual config

Most Common Prefix

/64

00000000 in decimal

0

Administrative distance cost for Connected

0

What is the backbone area of OSPF

0

What are the rules for wildcard masks?

0 must match, 255 is variable (or any number) It is reverse of subnet mask to calculate

Ethernet Types

0800 = IPV4 86DD = IPV6

Normal Register

0x2102

Register to allow password reset

0x2142

Administrative distance cost for Static

1

Default max address for Port Security?

1

What VLANS can a switch with VTP use?

1 - 1005 only

Class A Range

1 - 126

Class A addresses

1 - 126

Pins of a Rollover Cable

1 -> 8 2 -> 7 3 -> 6 4 -> 5 5 -> 4 6 -> 3 7 -> 3 8 -> 1

Routing between VLAN options

1 route per interface for every VLAN VLAN Trunks Layer 3 Switcher (intervlan routing)

Straight Through Cable (GE)

1-1 2-2 3-3 4-4 5-5 6-6 7-7 8-8

Straight Through Cable (FE)

1-1 2-2 3-3 6-6

CrossOver Cable (GE)

1-3 2-6 3-1 4-7 5-8 6-2 7-4 8-5

CrossOver Cable (FE)

1-3 2-6 3-1 6-2

What are the standard acl numbers?

1-99, 1300-1999

How much does IOS Buffer

10 Commands

Private A Range

10.0.0.0 - 10.255.255.255

Administrative distance cost for IGRP

100

What are he extended Acl Numbers

100-199, 2000,2699

What standard VLANS cannot be used?

1002 - 1005

Administrative distance cost for OSPF

110

Administrative distance cost for IS-IS

115

Administrative distance cost for RIP

120

10000000 in decimal

128

Class B Range

128 - 191

Class B addresses

128 - 191

if 48 bits for GP, how many subnet and host?

16 bits for subnets, 64 bits for host

Administrative distance cost for EIGRP (External routes)

170

Private B Range

172.16.0.0 - 172.31.255.255

11000000 in decimal

192

Class C Range

192 - 223

Class C addresses

192 - 223

Private C Range

192.168.0.0 - 192.168.255.255

Show IP NAT Statistics misses counters

1st - new packet needed an entry 2nd - when no available address to hand out

How many acls can an interface have

2 only! 1 inbound, 1 outbound

Administrative distance cost for BGP (external routes)

20

TCP Header

20 bytes

Administrative distance cost for BGP (internal routes)

200

11100000 in decimal

224

Class D addresses (MultiCast)

224 - 239

What is the multicast address for ospf?

224.0.0.5

11110000 in decimal

240

Class E addresses (Experimental)

240-255

11111000 in decimal

248

11111100 in decimal

252

11111110 in decimal

254

11111111 in decimal

255

Administrative distance cost for unusable

255

How many bits to hex digit?

4 bits

How long (usually) is the global prefix?

48

Default aging time for dynamic mac address learning

5 mins

Mac Address Size

6 bytes (48bits)

How many blocks in an ipv6 address?

8

UDP Header

8 bytes

10Base-T

802.3 100 meters 10Mbps

1000Base-T

802.3ab 100 meters 1000 Mbps

10GBase-T

802.3an Copper 100m 1000 Mpbs

IEEE autonegotiate

802.3u

100Base-T

802.3u 100 meters 100 Mbps

1000Base-LX

802.3z Fibre 5km 1000 Mbps

Administrative distance cost for EIGRP (internal routes)

90

Serial Config

9600 baud No Flow Control 8 bit ASCII No Parity 1 Stop Bit

Terminal Settings

9600 bits 8 data bits no parity 1 stop bit no flow Control (9600,8,N,1,N)

Unknown IPV6 address

::

Loopback ipv6 address

::1

User Exec Mode Symbol

> No changes to config

Private Networks

A 10.0.0.0 B 172.16.0.0 - 172.31.0.0 C 192.168.0.0 - 192.168.255.0

Mode

A button that cycles the meaning of the LEDs through 3 states STAT DUPLX SPEED

What indicates autonegotiation

A in show port command

what does a wildcard mask of 0.0.0.0 match?

A single host

Unicast Ethernet Address

A term for a MAC that represents a single LAN interface

Input Errors

A total of runts, giants, no buffer, CRC, frame, overrides and ignored

Time out acls can be based on what?

Absolute Timeouts Idle Timeouts

Trunk Modes

Access - Always access Trunk - Always a trunk dynamic desirable - Only one that initiates a trunk! dynamic auto - passive, waits for a trunk (desirable or trunk has to initiate)

Connection Point to End Users

Access Switches

Acl command for standard?

Access-list X permit/deny x.x.x.x (log)

Add a remark to an acl?

Access-list X remark

Connection Closedown

Ack,Fin -> Ack <- Ack,Fin <- Ack ->

Point-To-Point WAN link

Acts like an Ethernet trunk between two Ethernet switches

How do you get logs from acl?

Add log to end of access-list

What does 802.1q do to the frame?

Adds a 4 byte header

dot1q - What does it do to the packet

Adds a 4byte header, leaves rest of packet alone!

VLAN Tagging?

Adds a header changing the underlying fram

EIGRP uses what type of IGP

Advanced distance Vector

Late Collisions

After 64th byte - mostly caused by duplex mismatch

Global Unicast Prefix

All others that are not listed

Broadcast Address

An address that means "all devices that reside on this LAN right now" (FFFF.FFFF.FFFF)

OSPF uses

Areas. Most with Area 0 as backbone

What does Neighbor solicitation do?

Asks for solicited Node addresses

DAD is run when?

At first use and each time interface is brought up

What benefits does PPP have over HDLC?

Authentication (PAP) Error detection and recovery Multi-Protocol Support

Enable Secret?

Auto encrypts password in better encryption than Service Password-Encryption

What are the recommendations for zero subnet?

Avoid use if possible Implies the use of classful routing Routers have to be configured with ip subnet zero

Show Int Errors - Giants

Bad Nic or MTU

Shown after logon

Banner EXEC

Shown before login but after MOTD?

Banner Login

What are the 3 types of Banner?

Banner Login Banner Exec Banner Motd

Shown before login?

Banner MOTD

ROM

Bootstrap

What is stored on the ROM?

Bootstrap, Post, IOS

Bridges - Collision / Domain behaviour?

Bridges create collisions domains Do NOTHING to help broadcasts

Line up and protocol up

Cable plugged in and working

Line status up but protocol is down

Can be protocol mismatch - eg serial link

How does OSPF select the router id?

Can be sent manually Or uses highest logical loopback address (of no loopbacks, highest ip address)

Configuration Mode

Can make changes

What can Cisco switches without Autonegatiate

Can sense the speed

10Base-T Cable

Cat 3

10Base-T

Cat 3 or better 100m (328 feet)

100Base-T Cable

Cat 5

100Base-T

Cat 5 UTP or better (2pairs) 100m (328feet)

1000Base-T Cable

Cat 5e / 6

1000Base-T

Cat 5e UTP or better (4 pairs) 100m (328 feet)

CSU/DSU

Channel Service Unit/Data Service Unit- what routers connect to

Fragment Free

Checks first 64KB for corruption then forwards No FCS Check

Global Routing Prefix

Chunk of addresses for public services

Secondary Addressing

Cisco specific - allow another subnet to share a layer 2 domain Downside is traffic must go through the router

RIP protocol is the only routing protocol that is...

Classful!!!

EIGRP uses what metric

Composite of bandwidth and delay. Calculated on slowest link and cumulative dela

Classfull addressing

Concept of address having 3 parts - network, subnet, and host with the mask defined by Class A,B,C

Classless addressing

Concept that the address has two parts - prefix +host - no consideration of class

OSPF Hello Messages...

Contains IP header with IP port 89 set to multicase to 224.0.0.5 have to be same subnet

Command to set running config to start

Copy Run Start

How do you set the config?

Copy Running-Config Startup-Config

Aggregates Distribution Switches in a large complex

Core

OSPF uses what metric

Cost with the default being based on interface bandwidth

Collisions

Count of total collisions

Telnet - get back to access server?

Ctrl + Shift + 6 then X

Commands to go back to enable mode

Ctrl + z or end

CPD

Customer Premises Devices-devices owned by the customer

UDP 67,68

DHCP

UDP,TCP 53

DNS

What does a SLAAC packet NOT contain?

DNS Servers

FRAME Relay cable types

DTE / DCE

OSI Layer 2

Data Link Ex. 802.3, HLDC

DCE Cable

Data communications equipment; you pick the type of cable based on which cable the router is acting as

DTE Cable

Data terminal equipment; you pick the type of cable based on which cable the router is acting as

What is the default maximum MACs in port-security? and the command to change it?

Default is 1 Switchport port-security maximum X

What are the steps to use SSH?

Define a domain name (ip domain-name) Router MUST be named Generate keys (crypto key generate RSA) Have to have username / password set

Framing

Defines the meaning behind the bits that are transmitted across a network; in other words, it defines the meaning of the bits transmitted and received over a network

Ctrl+D

Deletes a single character

Is FCS detection or correction?

Detection only

CDP details

Device Identifier - Usually Hostname Address List - Network & DLL address Port Identifier - interface on remote router/switch Capabilities - List information on type of device Platform - Model and OS Level

CRC

Did not pass FCS - can be collisions

DS0

Digital Signal Level 0-refers to the standard for a single 64 kbps line

OSPF uses what type of algorithm

Dijkstra shortest path first

Port Security Protect?

Discards offending traffic DOES NOT log DOES NOT disable the interface

Port Security Restrict?

Discards offending traffic Logs Messages DOES NOT disable the interface

Port Security Shutdown?

Discards offending traffic Logs Messages Disables interfaces (goes into err-disabled)

Banner MOTD?

Displays before Authentication

Down arrow or Ctrl+N

Displays command down, buffer

Up arrow or Ctrl+P

Displays most recently used command, buffer

3 types of IGP

Distance Vector - Bellman Ford Advanced Distance Vector - balanced hybrid Link-State

Aggregation Point for Access Switches, Forwards frames between Distribution Switches

Distribution Switches

What would a switch do if sees source and destination on same port

Drop (filter) it

Show Int Errors - Collisions

Duplex Mismatch

Show Int Errors - Runts

Duplex Mismatch

What is DAD?

Duplicate Address Detection

ISL - What does it do to the packet?

ENCAPSULATES the WHOLE packet

Who wins out of enable password & enable service

Enable Service Wins

What command do you use to set dot1q?

Encapsulation command Has to be done before sub interfaces!!

Store and Forward?

Entire Frame Stored then forwarded After FCS Check

TCP Only Features

Error Recovery Flow Control Connection Establishment Ordered data transfer Data segementation

How often are OSPF Hello packets sent

Ethernet - 10 seconds Serial etc - 30 seconds

By default how often are RA sent?

Every 200 seconds

How often do routers reload LSAs

Every 30 mins or when something changes

What is the rule with routers in ospf and the backbone?

Every other area must be connected to a router in Area 0

Name the three config modes of a switch

Exec Priv Exec Config

Command to change timeout of session?

Exec-Timeout 0 0 first 0 is mins second 0 is seconds

Set the switch timeout?

Exec-timeout 5 (mins) Can be optional seconds

Command to go back one level

Exit

What is at the end of every ACL?

Explicit Deny

What is in an ethernet trailer?

FCS

Unique Local Prefix

FD

Link Local Prefix

FE80

Multicast Prefix

FF

All IPV6 hosts multicast address

FF02::1

what is the multicast address of dhcp servers and relays

FF02::1:2

v6 DHCP relay

FF02::1:2 - all dhcp agents Router changes multicast to unicast and forwards to dhcp server

What is the solicited node address

FF02::1:FF Last six digits of unicast addresses

What do solicited node addresses begin with?

FF02::1:FF (the last 6 digits of unicast)

All Routers Only multicast address

FF02::2

What are the multicast addresses for OSPFv3

FF02::5 FF02::6

OSPFV3 Routers Multicast address

FF02::5/6 224.0.0.5 / 224.0.0.6

EIGRP Routers Multicast address

FF02::A 224.0.0.10

Router Solicitation address

FF:02::2

How is autonegotiation done?

FLP (Fast Link Pulse)

TCP 21

FTP Control

TCP 20

FTP Data

Ethernet Header & Trailer Field: Start Frame Delimiter (SFD)

Field length: 1 | Signifies that the next byte begins the Destination MAC Address

Ethernet Header & Trailer Field: Length

Field length: 2 | Defines the length of the data field of the frame (either length or type is present, but not both)

Ethernet Header & Trailer Field: Type

Field length: 2 | Defines the type of protocol listed inside the frame (either length or type is present, but not both)

Ethernet Header & Trailer Field: Frame Check Sequence (FCS)

Field length: 4 | Provides a method for the receiving NIC to determine if the frame experienced transmission errors by the sender's calculations and then comparing this to the receiving device's calculations

Ethernet Header & Trailer Field: Data and Pad

Field length: 46-1500 | Holds data from a higher layer, typically an L3 PDU (generic), and often an IP Packet

Ethernet Header & Trailer Field: Destination MAC Address

Field length: 6 | Identifies the intended recipient of this frame

Ethernet Header & Trailer Field: Source MAC Address

Field length: 6 | Identifies the sender of this frame

Ethernet Header & Trailer Field: Preamble

Field length: 7 | Synchronization

What are the three things a switch can do to traffic?

Filter It Flood it Forward it

How do you deliminate for the Banners?

First non blank character is deliminator. So use something like "

IP route Brackets

First number is administrative distance, second is metric

What are the three places device will look for IOS, in order?

Flash TFTP Server ROM

Lights - Speed Flashing Green, Solid Green, Off

Flashing Green - Gig Solid Green - Fast Eth Off - Eth

Lights - Status Flashing Green, Solid Green, Flashing Amber / Green, Solid Amber, Off

Flashing Green - Traffic Flowing Solid Green - Ports up but NO traffic Flashing A / G - Link Fault Solid Amber - STP Off - Port Down

Runts

Frames that did not meet min 64 bytes - caused by collisions

Giants

Frames that exceed 1518 bytes

How to turn CDP on/off

Global no CDP run CDP run Per interface no cdp enable cdp enable

Where can CDP be disabled?

Global and per interface

where is OPSF enabled?

Globally

Where is OSPfV3 enabled?

Globally and per interface

Lights - Duplex Green, Off

Green - Full Off - Half

Meaning of Interface is up, line protocol is down

H/w Fine. issue is logic, serial Clock for example

Default protocol for Serial?

HDLC

Wan Types

HDLC Frame relay EoMPLS

TCP 80

HTTP

OSI Layer 7

HTTP, NFS

What must you do to switch port for ROAS

Has to be set to TRUNK, routers do not negotiate trunks It also has to be dot1q or ISL Has to be min Fast Eth

Hello and Dead Timer Defaults of OSPF

Hello 10 seconds, DEAD is 4 times the hello

HDLC

High-Level Data Link Control: main goal is delivering data across the link and to check for errors and identify the packet type; defines framing

RIP-2 uses what metric

Hop count

What devices allow a collision domain to spread

Hub

Devices that require cross over Pin 3,6

Hub Switches

Transmits on Pin 3,6

Hub Switches

What is stored on Flash?

IOS (retained on reload)

what command can you use to add/remove acl numbers?

IP Access-list

Prereqs for SSH

IP Domain-Name "DNS NAME" Crypto key generate RSA IP SSH Version 2 (optional but recommended)

Set static NAT

IP NAT inside source static

Set Dynamic NAT

IP NAT pool IP NAT inside source list

PAT (overload)

IP NAT pool IP NAT inside source list overload

How do you allow use of zero subnets?

IP Subnet-zero No IP subnet-zero disables it

Set ipv6 dhcp relay address

IP dhcp relay "destination address"

Command used to set dhcp helper?

IP helper-address

Static NAT

IP mapped to public IP

DNS Commands

IP name-server - set dns server IP host - static name no IP domain-lookup - disable dns resolver

Routing Protocols

IPV4 - RIPv2 OSPFV2 EIGRP IPV6 - RIPng OSPFv3 EIGRPV6

how to make interface use EUI

IPV6 address prefix EUI

To enable IPV6 routing

IPV6 unicast-routing

Trunking Protocols?

ISL - Interswitch Link - Cisco own old one 802.1Q - Todays standard

Types of Frame Tagging

ISL - more or less obsolete dot1q - use most

Speed

If on (green) each port LED implies the speed of the port as follows Off = 10Mbps Solid Green = 100Mbps Flashing Green = 1000Mbps

STAT (status)

If on (green) implies each port LED implies that port status

DUPLX (duplex)

If on (green), each port LED implies that ports duplex setting on/green = Full off = half

What is the duplex behaviour

If speed detected is 100mb or less, set to half duplex

Frame (error)

Illegal format frames - can be collisions

Light (SYST)

Implies the overall system status Switch Off = Off All OK = Green Switch not working = Amber

Cisco Express Forwarding

Improves on Fast and Process switching by Saving data link headers used for encapsulating packets using other table, with faster lookup time, before looking at the routing table organizing table using tree structures for fast searches

Fast Switching

Improves on Process Switching by Saving data link headers used for encapsulating packets using other table, with faster lookup time, before looking at the routing table

Expanding IPV6 addresses

In each quartet add leading 0's until quartet has 4 hex digits If double colon exists, count the quartets shown & add zeros up to 8 quartets

What are the 3 address names used in NAT

Inside Local - Private IPs Inside Global - Routable IPS Outside Global -The natted version

Shortening IPV6 addresses

Inside each quartet remove the leading zeros find any string of two or more quartets of zeros & replace with double colon - can only use once!! ALWAYS PICK THE LONGEST SEQUENCE

Add a management IP

Interface VLAN 1 ip address IP ip default-gateway IP (use if ip routing disabled) ip route 0.0.0.0 0.0.0.0 (use if ip routing enabled) No shutdown

Meaning of Interface is administratively down, line protocol is down

Interface is shutdown issue no shut

Ctrl+shift+6

Interrupts the current command

How to enable IP4 routing stack

Ip Routing

IP Route permanent is used for?

Is used to tell IOS keep the route alive even if the interface goes down

What happens when using key combination to get out of telnet

It SUSPENDS the session

What changes in show ip route if using outgoing interface in static route?

It shows as directly connected

What happens if you apply an acl to an interface which already has one?

It will overwrite it

How to remember all hosts address for ipv6?

Its every 1!!! FF:02::1

TCP 3 Way Handshake

Its for Session Establishment Syn -> <- Syn/Ack Ack ->

TCP 4 Way Handshake

Its for session teardown Fin/Ack -> <- Ack Ack/Fin -> <- Ack

What can u use with Standard ACLS?

Just SOURCE IP

Enter a suspended telnet session?

Just connection number Or Resume (connection number)

What is the solicited node address?

Just hosts with last 6 hex values same as dest ipv6 address

When is (Normal Link Pulse) NLP Sent

Just normal waiting

Line status refers to

Layer 1

Protocol status refers to

Layer 2

What defines a routing protocol?

Learns routes from neighbors Advertise routes to neighbors Picks the best routes If network topology changes pick a new route e.g link fails invoke convergence

What does disabling Service Password-Encryption do?

Leaves existing passwords encrypted Any new passwords will be clear text

How to set a console Password

Line Console 0 login Password Nathan

Set a Telnet Password

Line vty 0 15 login Password Nathan

OSPF uses what type of advertisement

Link State Advertisements LSA They are stored in the LSB Command to to show it is Show IP OSPF database

OSPF and ISIS use what type of IGP

Link-State

LAN

Local Area Network: protocols that define how to network between devices that are relatively close together

OSPF process ID is what...

Locally significant only!!

what doesnt the explicit deny on an acl do?

Log, you have to add you own deny to log

Protocol is xx always refers to what?

Logical

Enable Secret - encryption level?

MD5 Hash

OSI Layer 6

MIME SSL

What is the golden rule with Mac Addresses and IPs?

Macs change, but IPS remain the same

Backspace

Moves cursor backwards deleting characters

Left arrow or Ctrl+B

Moves cursor backwards without deleting characters

Right Arrow or Ctrl+F

Moves cursor forwards without deleting characters

Ctrl+A

Moves cursor to first character of the command

Ctrl+E

Moves cursor to last character of the command

Shorter Distance Fiber (suitable for LED)

Multimode Fiber

1000Base-SX

Multimode Fiber 550m (1804.5 feet) - 50 Micron

1000Base-LX

Multimode Fiber 550m (1804.5 feet) - 50 Micron & 62.5 Micron

Does one ospf process id know the routers from another process id on the same switch?

NO

How to set router as master ntp?

NTP Master X (this is stratum number, cannot be 1)

How to set the NTP server?

NTP Server x.x.x.x

3 Places to look for Startup file, in order?

NVRAM TFTP Server Setup Mode!

What happens if one switchport set to trunk and the other end set to access

Native VLAN will pass across

What are the 3 types of methods OSPF uses to build routes?

Neighbors - Relationship between two routers Database exchange - Process of sending LSAs Adding the best routes - running SPF to calculate best routes.

OSI Layer 5

Netbios

OSI Layer 3

Network IP. ARP

Does process id have to match area id in ospf?

No

Does show running-config show VTP VLANS?

No

Encryption level of enable password by default?

No Encryption

HDLC Type Field

No but Cisco added one; Won't work with any other router that's not Cisco

Disable CDP at interface

No cdp enable

Normal / Extended VLANS?

Normal - 1 - 1005 Extended 1006 - 4094

Internal Gateway Protocols

OSPF EIGRP

What is the difference about numbers between OSPF and EIGRP

OSPF doesnt care about process number, EIGRP cares about the AS number

What is the version of OSPF for ipv6?

OSPF3

What is a major difference between ospfv2 and v3?

OSPFv3 does not need to be on same segment, OSPFv2 does

Manufacturer Code Size

OUI 3 bytes (24bits)

Lights - RPS Off, Solid Green , Flashing Green, Solid Amber, Flashing Amber

Off - No RPS or it's off Solid - Connected Flashing Green - Connected but supplying another device# Solid Amber - Standby or Fault Flashing Amber - Internal PSU failed

What mode is the default for trunks on switches?

Older switches - dynamic desirable Now - dynamic auto

Multicast Address

On Ethernet, a multicast address implies some subset of all devices currently on the Ethernet LAN (0100.5exx.xxxx)

Standard ACLs

Only do source IP

Port Security - Protect

Only drops the frame

Banner Login?

Only shown on remote connections

Ethernet Address, NIC Address, LAN Address, Hardware Address, Physical Address

Other names often used instead of MAC address. These terms describe the 6-byte address of the LAN interface card

What two options are available to define the outgoing path for a static route

Outgoing interface Ip address

Devices that require cross over Pin 1,2

PC Router WAP

Transmits on Pin 1,2

PC Router WAP

TCP 110

POP3

what are the two allowed methods of an ACL

Permit and Deny

Interface is xx always refers to what?

Physical

Meaning of Interface is down, line protocol is down

Physical connectivity issues

OSI Layer 1

Physical-defines the standards and protocols used to create the physical network and to send the bits across that network "sending bits" Ex. Ethernet

What is impossible in Show int

Physically down but logically up!

What is in an ethernet header

Preamble Start Frame Delimiter (SFD) Destination source Type Data and Pad Frame Check Sequence(FCS)

What does show ipv6 interface brief NOT show?

Prefix

What does a SLAAC packet contain?

Prefix Prefix Length Router information

what mode do you set the clock in?

Priv Exec Mode

How do you place a user straight into priv exec mode?

Priv level 15

NAT Terms

Private ->inside local Public -> inside global Outside Global -> outside public Outside local - outside private

iPV6 Unique Local

Private IPV6 addresses

IPV6 Global Unicast

Public IPV6 addresses

PCM

Pulse Code Modulation-defines that an incoming analog voice signal should be sampled 8000 times per second, and each sample should be represented by an 8-bit-code

What does Switchport Nonegotiate do?

Puts port in permanent trunk mode but IGNORES DTP messages

OSPF Passive interfaces..

Quit sending hello messages ignore hellos received do not form neighbor relationships it still advertises the subnet

What type of packet is SLAAC?

RA

How does OSPF choose its RID?

RIDS are a 32 bit number If router-id is used - use that (manually) Any loopback address that is up, use highest numerical one otherwise highest numeric IP which are up but maybe not connected. E.g not shutdown RID is chosen at initialization e.g reload or clear ip ospf process

IPV6 Routing Protocols

RIPNG EIGRPV6 OSPFV3 MP BGP-4

4 types of storage in a Cisco Device

ROM Flash RAM NVRAM

How do you discover a router

RS packet sent to FF:02::2 router will respond with an RS IF the host has an ip, it will be unicast if no address response will be multicast to FF:02::1

Cut-Through

Reads MAC, then begins to forward No FCS Check

Store & Forward

Receives full frame before forwarding

Ctrl+R

Redisplays the command line with all characters

What do OSPF hello packets do?

Remind routers they are there allows neighbors to find each other

What dont hubs do with Auto negotiate

Respond to Auto-Neg messages, must be half duplex

Telnet Commands

Resume command to swap sessions Ctrl+shift+6 to disconnect

How to configure OSPF

Route OSPF (process id) Router ID Configure IP as loopback address network ip address wildcard-mask area commands Review this in book

What devices allow separation of broadcast domains

Router

Process a router goes through to get that of an address for a client

Router responds to ARP request with a Proxy Arp When the host talks to the router, the packet will be IP address of destination Host Mac Address of router interface

Symbol and level of Priv Exec Mode

Router# can reload! debug etc

Symbol and level of Exec Mode

Router> can ping, show etc

What is important about routers and trunking?

Routers DO NOT negotiate trunking!

Common mistake with OSPF

Routers HAVE to be on same network segment

How does a route work?

Routes compare IP to subnet ID and mas in routing Forwards to next hop address of interface

What is stored on RAM?

Routing info Running Config Lost at reload

What does show version list?

Run time Why last loaded IOS image Interfaces installed NVRAM RAM Flash Memory

How do you enable routing on a Layer 3 switch

SDM Prefer lanbase-routing (needs a reload) enable routing (no reload)

To enable routing at hardware level on supported switches

SDM prefer lanbase-routing Reload switch

TCP 25

SMTP

UDP 161

SNMP

TCP 22

SSH

TCP 443

SSL

What is the name for a vlan ip on layer 3 switches

SVI

Dynamic NAT

Same as static but mapping is automatic Uses a pool of IPs Clears IP Nat Translation - clears dynamic entries

What's a TCP PDU called

Segment L4PDU

Duplicate Address Detection (DAD)

Sends NS with address it wants to use IF NA response - duplicate If no NA response - can use address

How does DAD Work?

Sends an NS If it receives a response, duplicate address If no response, can use the address

NDP Route solicitation (RS)

Sent to all routers FF02::2

Router Advertisement (RA)

Sent to the unicast of the host in response to a RS FF02::1

Bridges

Separates Collision Domain

Enable a router as dhcp Server

Service DHCP IP DHCP Pool "name" -> this then takes you into dhcp config Network x.x.x.x /x

Encrypt Password

Service Password-Encryption Immediately encrypts passwords Any new password will be encrypted

CDP Status commands

Show CDP - Show if CDP is enabled globally and timers Show CDP interface - show if CDP is enabled per interface & timers Show CDP Traffic - lists global stats for CDP advertisements sent/received

CDP Commands

Show CDP Neighbors - one summary line about each neighbor Show CDP Neighbors detail - 15 lines per neighbor Show CDP Entry Name - as the detail command but just one neighbor

See CDP switches?

Show CDP neighbors

Show cdp stuff?

Show CDP traffic Show cDP neighbor int detail

History Buffer Commands

Show History History Size X Terminal History Size X

To check NAT config

Show IP NAT translations Show IP NAT statistics

OSPF Show Commands

Show IP OSPF interface Brief - lists all interfaces - even passive ones Show IP ospf interface - a single line mentions if its passive

See Status of SSH

Show IP SSH Show SSH

DHCP Show Commands

Show IP dhcp binding - lists info about each leased IP Show ip dhcp pool - lists config plus stats Show ip dhcp server statistics - list dhcp stats does not list exclusions - global command Show ip dhcp conflict - shows how address were added e.g arp or ping

IPV6 show commands

Show IPV6 interface brief Show ipv6 interface

commands to see ospfv3 info

Show IPv6 route ospf Show IPv6 ospf database Show IPv6 ospf neighbor Show IPv6 ospf interface x (brief)

How do you show the mac address table?

Show MAC - Address-table

See macs?

Show Mac address-table or show mac address-table dynamic

View NTP server info?

Show NTP associations

VLAN Troubleshooting

Show VLAN Brief (lists VLANs not Trunks!) Show VLAN Show VLAN ID X - shows both trunks and access ports

How do you view acls?

Show access-list

how do i see list of commands i have used?

Show history

how do you see the neighbors table of ipv6

Show ipv6 neighbors Expect to see a route for the router, this is different to ipv4

Troubleshooting OSPF commands (ipv6)

Show ipv6 ospf - show process Show ipv6 protocols - shows protocols Show ipv6 ospf interface - shows enabled interfaces Show ipv6 ospf interface brief show ipv6 ospf neighbor - lists neighbors show ipv6 ospf database - lsdb summary show ipv6 route ospf - ospf learned routes.

IPV6 routing show

Show ipv6 route "address" Shows which route would be used to reach the address

View telnet sessions?

Show sessions

Banner Exec?

Shows at exec mode, so immediately at console After logon on telnet

Administratively Down means only one thing...

Shut Down

Port Security Violation Modes

Shutdown Restrict Protect

Default violation mode for port security?

Shutdown (err-disabled)

How do you enable a shutdown port in port-security?

Shutdown then no shutdown

Port Security - Shutdown

Shuts port, transmits error to logs

NAT Overload (PAT)

Single IP overloads using Ports

1000Base-LX (9 micron)

Single Mode Fiber 5km (3.1 miles)

Longer Distance Fiber for Laser

Single mode Fiber

What are the 4 packets involved in DHCPV6

Solicit -> <- Advertise Request -> <- Reply

Extended ACLs

Source & Destination IP Source & Destination Port

NS packet makeup

Source is link-local of Host A Destination is multicase of Host B

How to create an EUI address

Split the 6 byte (12 hex digit) MAC into two halves Insert FFFE between the two. This makes 16 hex digits Invert 7th bit of int ID

Process Switching

Standard Switching

Where to places acls?

Standard acls - place close to destination Extended acls - place close to source

Cut-Through

Starts forwarding as soon as possible. Can propogate errors as doesn't receive FCS in time

What is stored in NVRAM?

Startup Config retained on reload

What are the two types of DHCP V6

Stateful Stateless (SLAAC)

DHCPv6 features

Stateful - same as ipv4 version EXCEPT FOR No router info given DORA is replace with Solicit, Advertise, Request, Reply Stateless used for SLAAC

How do macs show managed by port-security

Static

3 types of NAT mode?

Static - 1 to 1 mapping Dynamic - 1 to pool mapping PAT - port based, most common

Enable Password?

Stores password in clear text, only encrypted if use Service Password-Encryption

Flash Memory

Stores the IOS images

What are subinterfaces used for?

Subinterfaces are used to add multiple virtual interfaces on a vlan

How do you enable port security?

Switch Port-security on interface

Show Int Errors - Overruns or Throttles

Switch too busy

Names for the Mac Address Table

Switching table Context Address Memory

How to configure Port Security?

Switchport mode Access / Trunk Switchport port-security

To enable 802.1Q trunking

Switchport trunk encapsulation dot1q or isl

Connection Establishment

Syn Syn,ACK ACK

Out of TCP/UDP, which does Windowing?

TCP

OSI Layer 4

TCP , UDP

POP Port

TCP 110

FTP Transfer Port

TCP 20

FTP Control

TCP 21

SSH Port

TCP 22

Telnet Port

TCP 23

SMTP Port

TCP 25

HTTPS Port

TCP 443

HTTP Port

TCP 80

What must u use to be able to use port numbers in an ACL

TCP or UDP and Extended ACL

DNS Ports

TCP/UDP 53

UDP 69

TFTP

How do you enable IPV6 routing?

TWICE! once at global with ipv6 unicast-routing once at interface by applying an IP

How do you apply the EUI Rules?

Take the MAC address chop it in half Put in FFEE write out the first two digits in hex invert the 7th bit reapply value as first two digits

TCP 23

Telnet

Gateway of last resort is..

The "choosen" default route

Burned-in Address

The 6-byte address assigned by the vendor making the card (Also called Universally Administered Addresses (UAA))

What is the subnet-router anycast address?

The all zeros address in a host prefix It is reserved!

IEEE 802.3 standard defines

The location of the destination address field inside the string of bits sent across the Ethernet

What should the native vlan of the trunk be set to in ROAS

The physical interface should be same at both ends

Using ROAS, what does the hosts DG need to be set to?

The sub interface address

What do hubs do in relation to duplex?

They DO NOT respond to Negotiation messages, so will always be mismatched

What is special about link-local packets

They are NOT routed

How are trunk ports displayed in Show VLan?

They are NOT! the ports will be missing

Where are excluded address in cisco DHCP

They are outside the DHCP Pool

Routers do what with RA for themselves

They do not list them

What are unique-local unicast addresses?

Think the Private IP ranges All Begin with FD00:: /8

NA (neighbor advertisement)

This answers an NS with the MAC address of the host

How can debug be monitored

Through the terminal window

What additional command is used for a time based acl?

Time Range

what other types of ACLs are there?

Time based Dynamic

Where are OSPF Changes sent?

To the DR then to BR

Output Errors

Total Errors

Packet Output

Total Packet Count

VTP Modes

Transparent / Server / Client

Support Telnet & SSH

Transport Input All

Support No remote access protocols

Transport Input None

Support only SSH

Transport Input SSH

Support Telnet

Transport Input Telnet

SNMP Port

UDP 161

Syslog

UDP 514

DHCP V6

UDP 546/547

DHCP Port

UDP 67/68

TFTP Port

UDP 69

Link Local address points features

Unicast Local link only Auto generated Used commonly for overhead protocols FE80 prefix

What packet type will a switch use to forward to an unknown MAC

Unknown unicast

How long does debug stay enabled

Until user turns it off or switch reload Undebug All No debug All

Best Practice for Router Security

Use enable secret instead of enable password Use Radius Disable Telnet Disable HTTP service Disable CDP on ports to untrusted networks Disable both tcp/udp small services

Match a single host with extended acl?

Use host in command line

What happens if Autonegotiate fails

Use the slowest speed If speed is 10/100 use half duplex if 1000 use full duplex

To use Username / Password combination

User Login Local

AAA Authentication access modes

User to Switch Access -> SSH Switch to AAA Server -> RADIUS / TACACS

Show Int Errors - No Buffers?

Usually broadcast storm

How do you create VLAN?

VLAN X Name "Name" Interface "Int ID" Switchport Mode Access Switchport access VLAN X

Places that need separate IP subnets

VLANS P2P Serial Links EoMPLS Frame Relay PVC

Reasons a switch may prevent VLANS crossing switches?

VLANs has been removed from allowed list VLAN does not exist VLAN is administratively shutdown VLAN has been pruned by VTP STP has placed the trunk in block

VTP Client Mode

VLANs not kept, reloads from VTP

How do you disable VTP

VTP Mode Transport VTP Mode Off

VTP Server Mode

Vlans can be created, modified and deleted. Advertises its changes

VTP Transparent mode

Vlans can be created, modified and deleted. DOES NOT advertise its changes DOES forward VTP info from other switches

Dynamic Desirable

Wants to be a trunk port, will actively throw itself at the other port

Service Password-Encryption

Weak!!

What are the rules of Service Password Encryption?

When applied it immediately encrypts all existing passwords Will continue to encrypt new passwords while applied When removed it will stop encryption new ones but leave existing ones encrypted

When does an ACL stop?

When it finds its first match?

WAN

Wide Area Network: protocols that define how to network between devices that are relatively far apart

Dynamic Auto

Will become a trunk only if a Desirable one or static trunk initiates it

Trunk

Will become a trunk with anything put an access port!

What does EUI do if no MAC address i.e serial

Will choose the lowest numbered router interface

How do you erase NVRAM?

Write Erase (Old Command) Erase Startup-Config (Old Command) Erase NVRAM (Use this one)

What is different for named ACLS?

You HAVE to use IP access-list NOT access-list

To disable auto netgotiate

You have to configure both Speed & Duplex

What happens with OSPFv3 if no OSPFv2 is running

You would need to set the router-id to set the RID

What do you use to an acl to VTY?

access-class

IPV6 is....

an address of eight sets of four hex digits

OSPF Hello messages...

are sent on the hello interval

Neighbor Solicitation (NS)

asks for a host with a particular address (think arp) to send back an NA sent to solicited node address

where do you see the config register?

at the end of show version

Routing by link local address requires what?

both address and outgoing interface

What do you do work out route summarization

break ranges into binary and look for last common bit

Any address not beginning with FD is..

considered Global Unicast

lease count for dhcp is in....

days.

What is the default action behaviour for port-security? and command to change it?

default is shutdown switchport port-security violation (protect / restrict / shutdown)

OSPF command to advertise default route

default-information originate

How do you send a default route with OSPF

default-information originate Add ALWAYS to add it if its not in the remote routers routing table

Ctrl + D

delete one character

How do you disconnect a telnet session

disconnect (connection number)

OPSFV3 config command?

does not use network command uses sub interface

Where are exclusions set in dhcp?

done at dhcp global level

Port Security - Restrict

drops the frame, sends to logs

What is the default trunk mode?

dynamic auto

How often does VTP advertise?

every 5 mins

what does a wildcard mask of 255.255.255.255 match?

everything!

Show Interfaces X switchport

identifies the access VLAN & voice VLAN plus configured & operational mode of trunk

How do you spot an EUI Address?

if end of link-local matches the ip address, its an EUI

NVRAM

initial Startup Config

protocol down and line down

interface is NOT shutdown but physical layer issue. no cable or device at other end turned off

Add an acl to an interface?

ip access-group x in/out

default route is...

ip route 0.0.0.0 0.0.0.0 and outgoing interface

To set an ipv6 address

ipv6 address "address"/Prefix

Set interface to SLAAC

ipv6 address autoconfig

Set interface to use DHCP (ipv6)

ipv6 address dhcp

Set ipv6 default route

ipv6 route ::/0 "interface id"

how do you set the equivalent of the default route for ipv6

ipv6 route ::/0 (next hop address)

Pattern to subnets?

is 256 minus the mask e.g 256 - 128 = 128 256 - 192 = 64

What is a /32 address on a router?

it's a route for its own IP

how do you name a static route

just add name "name" at the end of the ip route command

SLAAC features

learns prefix via NDP RS/RA Choose IP Uses DAD Use NDP to get default route Use stateless dhcp to get dns servers

Show mac address-table

lists mac & vlan ip - useful in exams if no other commanda

Neighbor Advertisement (NA)

lists sender address as target with MAC sent to the unicast address of the host who sent the NS

how do you get console to stop interrupting?

logging synchronous

How do you get the terminal message to put the command on the next line after message?

logging synchronous - for console you have to be in line console 0

login vs login local

login local uses username and password login just password

Esc + b

move back one word

Ctrl + F

move forward one character

Esc + f

move forward one word

Ctrl + E

move to end of command

Ctrl + a

move to front of command

Ctrl + b

moves back one character

Disable CDP Globally?

no CDP run CDP is enabled by Default

How do you stop the switch interrupting terminal messages?

no logging console

Where do sub interfaces show?

on Show VLANs

Show interface status

only one to show duplex / speed settings!

how can you disable ospf on an interface

passive-interface int X or Passive-interface default (for all)

Administrative distances are..

per router and not shared Lowest numbers

Administratively down and Protocol down

port has been shut down

how do you set the exec level of a command

priv exec level x "command"

On router sub int you can

put ip on physical interface or dot1q

Fragment Free

receives first 64kb before forwarding

How does OSPFV3 generate its router-id

same as ospf

To detect conflicts in dhcp

server uses ping client uses arp

Set up static nat

set an interface to inside - ip nat inside set the outgoing to outside - ip nat outside set up nat ip nat inside source static x.x.x.x x.x.x.x.x

set up PAT

set an interface to inside - ip nat inside set the outgoing to outside - ip nat outside create an access-list (e.g 5) set up nat ip nat pool natpool x.x.x.x x.x.x.x (range of addresses) ip nat inside source list 5 int serial0 overload Use the outgoing interface instead of IP!

set up dynamic nat

set an interface to inside - ip nat inside set the outgoing to outside - ip nat outside create an access-list (e.g 5) set up nat ip nat pool natpool x.x.x.x x.x.x.x (range of addresses) ip nat inside source list 5 pool "natpool"

encapsulation command on a router?

sets the vlan not the sub int ip (check)

how do you see a description of interfaces

show int descriptions

to see trunk info?

show interfaces trunk show interfaces switchport

how do you show all interfaces

show ip int brief

See NAT info?

show ip nat translations show ip nat statistics

How do you check the status of ospf on an interface

show ip ospf int x

What can you use with Extended ACLS?

source, destination, ports and protocol

Light (RPS)

suggests the status of the extra power supply

To disable trunking negotiation

switchport nonegotiate

Predefine MACs in port-security?

switchport port-security mac-address

How to configure "stick" MACs in port-security?

switchport port-security mac-address sticky

BGP is...

the only EGP protocol used today (exterior gateway protocol)

What must you remember on an extended acl?

to put an any any on deny or allow (if needeD)

where does the prefix / need to be

up against the IP

Creating a local unicast address

use FD as first 2 hex digits add unique 40 bit global id - gives a 48 bit Next 16 bits are subnet 64 bits for interfaces

Named ACLS

use acl subcommand NOT global can edit individual lines

How do you go back to enable mode

use end or Ctrl+z

How do you move from interface to global config

use exit

What masks do acls use?

wildcard Masks

RAM

working storage running config lives here