Networking Questions 2016 Part 5

Here are some more very random networking questions based around the CCNA type of exam head scratchers... :-)

1. What type of NAT allows you to map multiple unregistered IP addresses to a single registered IP address?

A) Static NAT
B) Dynamic NAT
C) Overloading (Port Address Translation)

2. Each port on a switch is a separate broadcast domain?

A) True
B) False

3. Inter-Switch Link and IEEE 802.1Q are types of...

A) Spanning Tree Protocol
B) Trunking method
C) Ethernet
D) Routing protocol

4. What statement is not correct when talking about a shared-medium Ethernet LAN?

A) The data frame broadcast delivery nature of Ethernet can have a negative affect on performance
B) Adding repeaters and hubs to an Ethernet network can increase latency
C) Ethernet is a best-effort delivery service
D) Collisions are caused by CSMA/CD on an Ethernet network

5. What TCP/IP layer are TCP and UDP protocols associated with?

A) Application
B) Host-to-Host
C) Internet
D) Network Access

6. What IOS command would you issue in privileged-mode to change the Cisco router configuration stored on TFTP?

A) config t
B) config mem
C) config net
D) config tftp









1. Answer: C

PAT (Port Address Translation) allows you to map multiple unregistered IP addresses to a single registered IP address.

2. Answer: B

Switches create separate collision domains but a single broadcast domain.

http://en.wikipedia.org/wiki/Broadcast_domain

3. Answer: B

Both Inter-Switch Link and IEEE 802.1Q are types of VLAN identification.  Inter-Switch Link (ISL) is a Cisco proprietary protocol whereas IEEE 802.1Q is a standard method of frame tagging.
4. Answer: D (did you get the "not"?)

Carrier Sense Multiple Access / Collision Detection (CSMA/CD) is a set of rules determining how network devices should respond when two devices try to use the shared medium simultaneously.

http://en.wikipedia.org/wiki/Carrier_sense_multiple_access_with_collision_detection
5. Answer: B

TCP and UDP protocols are associated with the Transport layer of the TCP/IP model, which is sometimes referred to as the "host-to-host transport layer".

http://en.wikipedia.org/wiki/Internet_Protocol_Suite

Internet protocol suite examples:
Application layer
BGP · DHCP · DNS · FTP · HTTP · IMAP · LDAP · MGCP · NNTP · NTP · POP · ONC/RPC · RTP · RTSP · RIP · SIP · SMTP · SNMP · SSH · Telnet · TLS/SSL · XMPP ·
Transport layer
TCP · UDP · DCCP · SCTP · RSVP 
Internet layer
IP  (IPv4 · IPv6) · ICMP · ICMPv6 · ECN · IGMP · IPsec  
Link layer
ARP · NDP · Tunnels  (L2TP · PPP · MAC  (Ethernet · DSL · ISDN · FDDI ·

6. Answer: C

To change the router configuration stored on TFTP you use configure network (config net)


More random question coming soon :-)

   “Employ your time in improving yourself by other men's writings, so that you shall gain easily what others have labored hard for.”

? Socrates

IPV4 Subnetting Tips

It always takes a bit to get your head around subnetting for the first time, and even more to answer the exam questions they give as they often are designed to trick you.

For random IPV4 subnetting questions to hone your skills, I suggest you bookmark:

http://www.subnettingquestions.com/

Memorizing the tables help immensely,  although at first appearance they appear daunting.

/24	8	255.255.255.0	256 = 28	Large LAN
/25	7	255.255.255.128	128 = 27	Large LAN
/26	6	255.255.255.192	64 = 26	Small LAN
/27	5	255.255.255.224	32 = 25	Small LAN
/28	4	255.255.255.240	16 = 24	Small LAN
/29	3	255.255.255.248	8 = 23	Smallest multi-host network
/30	2	255.255.255.252	4 = 22	"Glue network" (point to point links)
/31	1	255.255.255.254	2 = 21	Point to point links (RFC 3021)
/32	0	255.255.255.255	1 = 20	Host route

TIPS:

Remember the binary number doubles for each bit.  2, 4, 8, 16, 32, 64, 128, 256 etc

Also remember 8, 16, 24, 32 for the 8 bit block sizes. 

To find the block size, find the first octet that is not 255, then subtract it from 256... eg subnet mask of 255.255.255.224 ...256 - 224 = block size of 32 

Subtract 2 from the block size to get the number of hosts eg 32 - 2 = 30 host IP.
(network and broadcast addresses cannot be used for user IP)

For the slash format, eg /27 subtract 27 from 32 to give a remainder of 5
Then if we count up 5 times doubling, 2, 4, 8, 16, 32 we get to the same block size of 32.

We also see that 224 is equal to 3 subnet bits taken from the octet ( 11100000) in a C class subnet, this will equal 8 subnets (allowing for subnet zero) 1, 2, 4 = 7+1 = 8 subnets.


Some providers have questions relating to old routing kit that did not allow the use of the all "1" subnet or all the "0" subnet (known as 'subnet zero').On all new Cisco routers, the number of subnets is calculated using the formula of 2^n by default. However, for legacy routers network engineers use 2^n - 2 to comply with the almost obsolete RFC 1878 standard. 

Some text books and courses that relate to old routing equipment also refer to the old formula as do some Microsoft Learning courses. If you're planning to take a non-Cisco exam that involves subnetting you should make sure you understand the 'subnet zero' concept' and check what is considered the default correct formula by your examining board

Once you get the patterns 2, 4, 8, 16, 32, 64, 128, 256, 512, 1024, 2048, etc and the masks 255, 254, 252, 248, 240, 224, 192, 128 burnt in it will become way easier :-)

Networking Questions 2016 Part 4

Been a while since we've stretched the grey matter, time to get to some more thinking with these random networking questions :-) Have fun.


1. In which layer of the OSI model does framing occur?

A) Layer 3
B) Physical layer
C) Application layer
D) Layer 2
E) Network layer

2. How would you view the current Cisco Configuration Register value?

A) show config-register
B) show reg
C) show config
D) show version

3. What does 'r' stand for in the capabilities of a Cisco device in the output of a show cdp neighbor command?

A) Repeater
B) Router
C) IGMP
D) Host
E) Switch

4. Ethernet technology relates to which type of network?

A) WAN
B) LAN
C) MAN
D) SAN
E) All of the above

5. What is the numerical value of the Bridge Priority held by Catalyst switches?

A) 32500
B) 32768
C) 100
D) 1024
E) 32700

6. What OSI layer does the following refer to?

"Establishes availability of intended communication partners, establishes agreement on procedures regarding error recovery and data integrity and synchronizes networked applications"

A) Transport layer
B) Session layer
C) Datalink layer
D) Application layer
E) Presentation layer

7. PPP can be used over what types of serial connections?

A) Synchronous
B) Asynchronous
C) Both
D) Neither

8. Which of the following could be a valid MAC address?

A) 00-08-74-CE-B7-90
B) 192.168.0.1
C) FFFF.FFFF.FFFF.FFFF
D) 255.255.255.240




-->
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1. Answer: D

The protocol data unit (PDU) of the Data Link layer (Layer 2) is the frame.  Data passed down from the Network layer is framed at layer 2 before being sent on to the Physical layer.

http://en.wikipedia.org/wiki/Data_Link_Layer

2. Answer: D

You can see the current value of the configuration register by using the show version command.
eg:
Configuration register is 0x2102


3. Answer: A

 Router#show cdp neighborsCapability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge                  S - Switch, H - Host, I - IGMP, r - Repeater

 4. Answer: B

The IEEE standards relating to Ethernet technology were originally developed for local area networks.
This is the Cisco definition, although in practice this definition is very blurred :-).

 5. Answer: B

The Bridge Priority is the numerical value held by switches. All Catalyst switches have a default priority of 32768. To determine the root bridge you combine the priority of each bridge with its MAC. If two switches have the same priority value the lowest MAC address becomes the root bridge.

6. Answer: D


The Application layer of the OSI model (layer 7) establishes availability of intended communication partners, establishes agreement on procedures regarding error recovery and data integrity and synchronizes networked applications.

http://en.wikipedia.org/wiki/Application_Layer


7. Answer: C 

Point-to-Point Protocol (PPP) can be used over ISDN (synchronous) and dial-up (asynchronous) connections.

8. Answer: A

The standard format for printing MAC addresses is six groups of two hexadecimal digits, separated by hyphens (-) or colons (:) e.g. 00-08-74-CE-B7-90, 00:08:74:CE:B7:90.
Another convention commonly used is three groups of four hexadecimal digits separated by dots e.g. 0573.4567.19ab.

How did you go??

I told you they would be random, more coming, stay tuned.