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CCNA > Chapter 41 - Miscellaneous IP Services > Flashcards

Chapter 41 - Miscellaneous IP Services Flashcards

1
Q

What is FHRP?

A
  • First Hop Redundancy Protocol
  • Refers to a group of protocols that provide redundancy for the default gateway of a network by allowing multiple routers to be a backup for the address.
  • The 3 FHRPs are:
    - HSRP - Hot Standby Router Protocol - Cisco proprietary - Active/Standby - Load balancing per
    subnet/VLAN
    - VRRP - Virtual Router Redundancy Protocol - IETF - Master/Slave - Load balancing per subnet/VLAN
    - GLBP - Gateway Load Balancing Protocol - Cisco proprietary - AVG/AVFs - Load balancing per host
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2
Q

What is a Single Point of Failure?

A

A component that, if it fails, could bring down part of a network

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3
Q

What steps do FHRPs follow as their general function?

A
  1. All routers have a virtual IP address that all hosts list as their Default Gateway
  2. The routers exchange FHRP messages to agree which router does what work at what time
  3. When a router fails, the other routers use FHRP to decide which router takes over from the failed router
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4
Q

True or False. For HSRP the virtual IP can be any address.

A

False. It has to be in the same subnet as the hosts and physical interfaces.

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5
Q

True or False. When a new router takes over as the Active, any connected hosts must send new ARP requests.

A

False. The MAC address and IP address of the virtual interface are the same regardless of what router is Active.

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6
Q

True or False. When a new router takes over as Active, any connected switches’ MAC address tables will remain the same.

A

False. When a new Active takes over, it will broadcast a frame with the MAC of the virtual interface as its source MAC. The switches will update their MAC addresses in accordance with the interface this was received on.
This is a GARP (Gratuitous ARP) as it is an unsolicited ARP Reply.

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7
Q

What does a redundancy approach of Active/Standy mean?

A
  • All hosts send their packets destined for other networks to the Active router only.
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8
Q

True or False. The Active router can be configured per subnet

A

True.

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9
Q

What is SNMP?

A
  • Simple Network Management Protocol
  • Most popular versions are SNMPv2c and SNMPv3
  • Application layer protocol
  • Provides a messaging format for communication of stats and variables between SNMP Managers and Agents
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10
Q

What is an SNMP Manager?

A
  • A Network management application running on a PC or server. This host is known as an NMS (Network Management Station)
  • Uses UDP port 162
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11
Q

What is an SNMP Agent?

A
  • Software that is running on a managed device with knowledge of all variables on the device that describe it’s configuration, status, and counters.
  • The database that stores this info is called a MIB (Management Information Base).
  • Uses UDP port 161
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12
Q

What messages does an SNMP NMS use to poll an Agent for information?

A

Read message class:
- Get - Retrieve the value of a variable (OID)
- GetNext - Discover the OIDs available in an Agent’s MIB
- GetBulk - A more efficient version of GetNext that was introduced in SNMPv2

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13
Q

What message does an SNMP NMS use to edit information on an Agent?

A

Write message class:
- Set - Used to change the value of one or more variables (OIDs).

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14
Q

What messages does an Agent use to send unsolicited messages to an SNMP NMS?

A

Notification message class:
- Trap - Used to send unsolicited updates when a variable changes. These are not reliable as there is no error detection or correction.
- Inform - Used to send unsolicited updates when a variable changes. Unlike Traps these are reliable. They wait for an acknowledgement from the NMS.

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15
Q

What message does an Agent use to respond to a request from an NMS?

A

Response message class:
- Response

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16
Q

What transport layer protocol does SNMP use?

A

UDP

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17
Q

What is the difference between Traps and Informs?

A
  • Traps have no reliability and will not attempt error recovery after being sent
  • Informs still use UDP but have application layer reliability. If an Inform is not acknowledged by the NMS, the Agent will resend.
  • Because of this, Traps use less overhead Informs
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18
Q

What does a MIB do?

A
  • Management Information Base
  • Contains variables in the form of OIDs (Object IDs) that a Manager can monitor/control.
  • OIDs are listed in a hierarchical order. For example 1.3.6.1.2.1.1.5 will contain SysName for a device.
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19
Q

List security measures that can be used for SNMP?

A
  • ACLs to limit SNMP communications to those from known servers
  • Use a strong Community string
  • (SNMPv3 Only) Message Integrity - Confirms whether a message has been changed in transit
  • (SNMPv3 Only) Authentication - Allows authentication with both a username and password, the password never being sent as clear text. Instead it is hashed.
  • (SNMPv3 Only) Encryption - Encrypts the contents of SNMPv3 messages
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20
Q

What is an SNMP Community?

A
  • Also known as Community String
  • Clear text password that Agent and Manager have to know in order to communicate
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21
Q

What is an RO and RW Community?

A
  • RO - Read Only Community - Allows only Get messages from the Manager
  • RW - Read-Write Community - Allows Get and Set messages from the Manager
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22
Q

What is the difference between SNMPv2 and SNMPv2c?

A

SNMPv2 was the original implementation of SNMPv2 which did not include Communities. SNMPv2c includes Communities.

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23
Q

How to upgrade Cisco IOS

A
  1. Obtain the IOS image
  2. Place the IOS image somewhere that the router can reach. These can be external FTP/TFTP servers or external storage (e.g. USB flash)
  3. Use the ‘copy <method> flash' command. Method will be where it is being copied from (e.g. TFTP).</method>
  4. Then to ensure the device upgrades to the latest version use ‘boot system <filepath>' from global configuration. If this is not done then the router will just use the first IOS file it finds in flash which could be the previous.</filepath>
  5. Also make sure to save before reloading
24
Q

What command could you use to see if the IOS upgrade has been successful?

A

‘show flash’ - To ensure it has been downloaded

25
Q

What command can you use to validate the IOS version that you have installed to a Cisco device?

A

‘verify /md5 <filename> <md5>'</md5></filename>

The md5 hash will be checked against the one the Cisco have encoded into the file. This can be found on the Cisco download site for the file. If they match then the file is legitimate.

26
Q

List file transfer protocols

A

TFTP - Trivial File Transfer Protocol - Not encrypted
FTP - File Transfer Protocol - Not encrypted
SCP - Secure Copy Protocol - SSH encrypted
FTPS - File Transfer Protocol over SSL/TLS - Encrypted with SSL/TLS (Upgrade to FTP)
SFTP - SSH File Transfer Protocol - Encrypted with SSH (It’s own protocol)

27
Q

What are some of the FTP functions?

A
  • Navigate Directories
  • Add/remove directories
  • List files
  • File Transfer - GET (Receiving) PUT (Sending)
28
Q

What are the two connections used in FTP exchanges?

A
  • Control Connection (TCP Port 21) - Exchange FTP commands
  • Data Connection (TCP Port 20) - Exchange actual data. This includes output messages to display to a user.
29
Q

What command does an FTP Client use to define what random port the server should use to initiate the Data Connection?

A

FTP PORT

30
Q

What benefits does FTP Passive mode have over FTP Active mode?

A
  • In FTP Passive mode, the client initiates both the Command Connection and Data Connection so the server isn’t blocked, which would likely happen in Active mode when the server attempts to initiatie the Data Connection.
31
Q

What message does an FTP client use to tell the FTP server it is using passive mode?

A
  • FTP PASV
  • This indicates to the server that it needs to provide its listening port for the client to initiate a Data Connection
32
Q

How does FTPS improve on FTP?

A
  • When using FTP the username and password are sent as clear text. When using FTPS, the Control Connection and Data Connection are encrypted. This includes the username and password.
  • FTPS uses TLS and digital certificates for security
33
Q

What command does an FTP client use to tell the FTP server to use TLS?

A

FTP AUTH

34
Q

What ports does FTPS use?

A
  • 21 for data and control when using explicit mode
  • 990 for control and 989 for data when using implicit mode. The FTP AUTH command is also not required
35
Q

What does the word Trivial in TFTP refer to?

A
  • The small amount of features that TFTP offers compared to FTP.
  • For example, you can get and put files but cannot change directories or list files. There is also no authentication required
36
Q

True or False. FHRPs are pre-emptive by default

A

False. They are non-preemptive. This means that the Active router will not give up its Active status even if the original Active router becomes available again.

37
Q

What multicast addresses does HSRP use to multicast Hellos to the other router in the HSRP setup?

A
  • HSRPv1 - 224.0.0.2
  • HSRPv2 - 224.0.0.102
38
Q

What are the HSRP virtual MAC address formats?

A
  • HSRPv1 - 00:00:0C:07:AC:XX (XX being HSRP group number)
  • HSRPv2 - 00:00:0C:9F:FX:XX (X:XX being HSRP group number)
39
Q

Benefits of HSRPv2 over HSRPv1

A
  • HSRPv2 virtual MACs have 3 hexadecimal characters dedicated to the group number where as HSRPv1 only has 2. Meaning HSRPv2 can have more group numbers.
  • HSRPv2 can be used for IPv6. HSPRv1 can only be used for IPv4.
40
Q

Differences between HSRP, GLBP, and VRRP

A
  • HSRP uses Active and Standby for its routers. VRRP uses Master and Backup. GLBP uses a single AVG (Active Virtual Gateway) and upto 4 AVFs (Active Virtual Forwarder).
  • VRRPs multicast address is 224.0.0.18. HSRPs are 224.0.0.2 for v1 and 224.0.0.102 for v2. GLBP also uses 224.0.0.102.
  • VRRP uses the virtual MAC format 00:00:5E:00:01:XX. HSRPv1 uses 00:00:0C:07:AC:XX and HSRPv2 uses 00:00:0C:9F:FX:XX. GLBP uses 00:07:B4:00:XX:YY.
  • VRRP is IEEE standard. HSRP and GLBP are Cisco proprietary.
  • VRRP and HSRP can load balance between subnets/VLANs. GLBP can load balance within subnets and VLANs (e.g. Some hosts in a subnet can use one AVF and some can use another).
41
Q

What is the VRRP virtual MAC address format?

A
  • 00:00:5E:00:01:XX (XX being VRRP group number)
42
Q

What is the GLBP virtual MAC address format?

A
  • 00:07:B4:00:XX:YY (XX being GLBP group number and YY being AVF number)
43
Q

What commands can you use to configure HSRP?

A
  • To change to HSRPv2:
    ‘standby version 2’
  • To create a HSRP group
    ‘standby <group>' (group number must match between HSRP routers)</group>
  • To set the default gateway (Virtual IP) of a group
    ‘standby <group> ip <ip>'</ip></group>
  • To set the priority of a HSRP router (which one is more likely to become active (default 100). Only works if priority is higher than standby)
    ‘standby <group> priority <priority>'</priority></group>
  • To enable preemption
    ‘standby <group> preempt'</group>
44
Q

How is the Active HSRP router chosen?

A

In this order:
- Highest priority
- Highest IP on HSRP interface

45
Q

True or False. Two HSRP routers can be on different versions and still be able to communicate.

A

False. They must both be on either HSRPv1 or HSRPv2.

46
Q

What are the main operations of SNMP?

A
  • For Agents to notify the NMS of events
  • For the NMS to query Agents for status information
  • For the NMS to make configuration changes to Agents
47
Q

What commands can you use to configure a device as an SNMP Agent?

A
  • To provide optional SNMP information (e.g. Location, Contact)
    ‘snmp-server contact <contact>'
    'snmp-server location <location>'</location></contact>
  • To create a Community
    ‘snmp-server community <community> <ro/rw>' (ro=Read Only rw=Read/Write)</community>
  • To specify the NMS, version, and community
    ‘snmp-server host <ip> version <1,2,2c,3> <community>'</community></ip>
  • To specify that traps are sent to the NMS and what they are sent for
    ‘snmp-server enable traps <trap>'</trap>
48
Q

What are the default Cisco community names?

A
  • ‘public’ for read only
  • ‘private’ for read/write
49
Q

What are FTP and TFTP?

A
  • Industry standard protocols used to transfer files over a network
50
Q

What port does TFTP use?

A

UDP 69

51
Q

True or False. TFTP has built in reliability.

A

True. Ack messages are used to confirm that files have been received.

52
Q

What is Lock-Step communication?

A
  • Used by TFTP
  • A method of data transmission whereby a client/server will send a file and the recipient client/server will respond with an acknowledgement.
  • If an acknowledgement is not responded to with more data messages, this likely means that the acknowledgement did not reach the recipient so it will be retransmitted.
53
Q

True or False. TFTP servers respond to clients from port 69.

A

False. TFTP packets are sent to port 69 but when the server responds it will choose a random port as its TID (Transfer Identifier). The client will then continue responding to this TID.

54
Q

True or False. In FTP, Active and Passive only apply to the Data connection.

A

True. Because the client always initiates the Control connection, but Data is variable.

55
Q

What commands do you use to set the username and password that your device will use to login to an ftp server?

A
  • ‘ip ftp username’ in global config
  • ‘ip ftp password’ in global config
56
Q

How often are HSRP Hellos sent?

A
  • Every 3 seconds by default
  • Sent by routers in the Active, Standby, and Speak states
57
Q

HSRP States

A
  • Initial - HSRP not enabled
  • Learn- VIP not determined and no Hello received. Waiting for Hello
  • Listen- VIP determined. Waiting for Hello
  • Speak - Router sends Hellos and is actively participating in election.
  • Standby - Router is a candidate to become next Active router and sends Hellos.
  • Active - Router is forwarding packets sent to VIP. Router sends periodic Hellos.

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