Cisco Based Networking questions - part xi

Another set of 6 random IT questions to active your grey matter :-)

1. Hosts on one VLAN that want to communicate with another VLAN need to go through a router.

A) True
B) False

2. Triggered updates are used to speed the network convergence process?

A) True
B) False

3. What process is used to check whether packets have been received when using IP?

A) Acknowledgments
B) CRC
C) Windowing
D) Flow control
E) None

4. What is the administrative distance of RIP?

A) 110
B) 1
C) 120
D) 90
E) 100

5. What Cisco IOS command executes the configuration stored in NVRAM.

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

6. Where would you place extended access lists?

A) As close to the destination as possible
B) As close to the source as possible





1. Correct Answer: A
VLANs act as if they are different networks.  So communication between VLANs require routers.

2. Correct Answer: A
A triggered update is sent immediately in response to a change in the network (e.g. A link going down). The router detecting the change immediately sends an update message to its adjacent routers, which then generate their own triggered updates. This process continues until the network converges. Triggered updates occurs independently from the regular routing updates and are intended to speed the convergence process.

3. Correct Answer: E
Trick question. IP provides NO form of error correction/acknowledgements.

4. Correct Answer: C
Here in the question the A is administrative distance 110 for OSPF, B is 1 for Static Route, D is 90 for Internal EIGRP, E is 100 for IGRP so the last C is 120 for RIP.

5. Correct Answer: B
config mem executes configuration commands stored in NVRAM by copying startup-config to the running-config

6. Correct Answer: B
Extended access lists are much more granular than standard ACLs, you can block specific ports or protocols. To avoid unnecessary traffic on your network place them as close to the source as possible.

Cisco based exam questions - part x

Part 10 of random Cisco CCNA based questions to stimulate some thought or just refresh - enjoy


1. What command would you use to erase the startup config of a router?

A) erase nvram
B) erase flash
C) delete startup
D) erase startup
E) delete run

2. HDLC is ISO standard WAN protocol which means you don't need Cisco routers at both ends of a WAN connection, a router from any vendor that supports HDLC will work.

A) True
B) False

3. When you connect to a remote router "out-of-band", via what port would you connect with?

A) Console port
B) Auxiliary port
C) Ethernet port
D) Serial port

4. What is the IEEE standard describing VLANs called?

A) IEEE VLAN
B) 802.3
C) 802.1q
D) 802.11b
E) 802.3q

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

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

6. What do asymmetric switches require?

A) memory buffers
B) extra ports
C) statically assigned ports only
D) high speed CAM







1. Correct Answer: D
To erase the startup configuration use the following command:

Router#erase startup-config
or
Router#erase startup

2. Correct Answer: B
Even though HDLC is an ISO standard, each vendor has their own implementations of HDLC.

3. Correct Answer: B
When a router is out-of-band (out of the network) you would connect remotely via a modem attached to the auxiliary port.

4. Correct Answer: C
The IEEE 802.1Q standard specifies a standard method for inserting virtual LAN (VLAN) membership tags into Ethernet frames.

5, Correct Answer: C
Point-to-Point Protocol (PPP) can be used over ISDN (synchronous) and dial-up (asynchronous) connections.

6. Correct Answer: A
With ability for support of high bandwidth ports Asymmetric Switches require more Buffer memory for storing & forwarding of packets for fast processing. 

How did you go? couple of tricky ones there huh :-)

More coming, stay tuned!

Subnets and subnet masks

One of the most complex tasks TCP/IP has to perform is to determine whether or not a given IP address exists on the same subnet. The task isn’t really that complicated once you understand how TCP/IP uses its IP address and subnet mask, here's a very basic rundown.

An IP address looks something like this: 192.168.10.52. IP addresses always contain four numbers from 0–255, separated by periods. A portion of the IP address is called the network ID and acts as a unique identifier for a particular subnet.

The rest of the IP address is called the host ID and identifies a particular computer or network device on that subnet uniquely. How can you tell which part of the IP address is which? By using the subnet mask. A subnet mask looks a lot like an IP address, with four groups of numbers: 255.255.255.0. Remember, computers are binary machines that can understand only in zeros and ones. For the subnet mask to make sense, you have to translate it and the IP address into binary.
 

TIP: You can switch the Windows Calculator into Scientific view, which enables you to convert numbers from decimal to binary.


Convert all the four groups (octets) of numbers into binary code. For example, an IP address of 192.168.10.41 and a subnet mask of 255.255.255.0 look like this in binary:


Address or Mask 1st octet 2nd octet 3rd octet 4th octet

192.168.10.41 11000000 10101000 00001010 00101001

255.255.255.0 11111111 11111111 11111111 00000000



Everyplace you see a “1” in the subnet mask corresponds to the portion of the IP address that is the network ID. Everyplace you see a “0” in the subnet mask corresponds

to the portion of the IP address that is the host ID. Here, the network ID is 192.168.10, and the host ID is 41.TCP/IP treats everything with an IP address that starts with 192.168.10 as if it were on the same subnet. Any IP address that starts with something other than 192.168.10 is treated as if it existed on another subnet. 

 
Basic TCP/IP Services

A number of the protocols in the TCP/IP suite are considered core protocols, which means they are usually present on any network that uses TCP/IP. The core protocols provide basic services that no network can do without. These services include

_ Data transmission. Is handled by more than one protocol: the User Datagram Protocol (UDP) and the Transport Control Protocol (TCP). Computers use UDP when they need to send a small packet of data and don’t care if the remote computer actually receives the data. Computers use TCP when loads of data needs to be transmitted because TCP allows the remote computer to reply, confirming its receipt of the data.

_ Name resolution. Provided by the Domain Name System, or DNS, protocol. DNS enables people to use easy-to-remember names like www.microsoft.com and allows computers to translate those names to numeric IP addresses.

_ Windows Internet Name System (WINS). Prior versions of Windows also use WINS to convert computer names into IP addresses. Windows Server 2003 is compatible with WINS.


   “ We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths.”

― Walt Disney
 
References:
Sybex(2003): Mastering Windows Server 2003

Understanding Engineers

 The following is a collection of quotes gleaned from the pages of pprune.org replicated here for your enjoyment :-)

Understanding Engineers #1
Two engineering students were biking across a university campus when one said, "Where did you get such a great bike?" The second engineer replied, "Well, I was walking along yesterday, minding my own business, when a beautiful woman rode up on this bike, threw it to the ground, took off all her clothes and said, "Take what you want." The first engineer nodded approvingly and said, "Good choice: The clothes probably wouldn't have fit you anyway."

Understanding Engineers #2
To the optimist, the glass is half-full. To the pessimist, the glass is half-empty.
To the engineer, the glass is twice as big as it needs to be.

Understanding Engineers #3
A priest, a doctor, and an engineer were waiting one morning for a particularly slow group of golfers. The engineer fumed, "What's with those guys? We must have been waiting for fifteen minutes!"
The doctor chimed in, "I don't know, but I've never seen such inept golf!"
The priest said, "Here comes the greens-keeper. Let's have a word with him."
He said, "Hello George, What's wrong with that group ahead of us? They're rather slow, aren't they?"
The greens-keeper replied, "Oh, yes. That's a group of blind firemen. They lost their sight saving our clubhouse from a fire last year, so we always let them play for free anytime!."
The group fell silent for a moment.
The priest said, "That's so sad. I think I will say a special prayer for them tonight."
The doctor said, "Good idea. I'm going to contact my ophthalmologist colleague and see if there's anything she can do for them."
The engineer said, "Why can't they play at night?"

Understanding Engineers #4
What is the difference between mechanical engineers and civil engineers?
Mechanical engineers build weapons . Civil engineers build targets .

Understanding Engineers #5
The graduate with a science degree asks, "Why does it work?"
The graduate with an engineering degree asks, "How does it work?"
The graduate with an accounting degree asks, "How much will it cost?"
The graduate with an arts degree asks, "Do you want fries with that?"

Understanding Engineers #6
Three engineering students were gathered together discussing who must have designed the human body. One said, "It was a mechanical engineer . Just look at all the joints".
Another said, "No, it was an electrical engineer. The nervous system has many thousands of electrical connections".
The last one said, "No, actually it had to have been a civil engineer. Who else would run a toxic waste pipeline through a recreational area?"

Understanding Engineers #7
Normal people believe that if it ain’t broke, don't fix it.
Engineers believe that if it ain’t broke, it doesn't have enough features yet.

Understanding Engineers #8
An engineer was crossing a road one day, when a frog called out to him and said, "If you kiss me, I'll turn into a beautiful princess".
He bent over, picked up the frog, and put it in his pocket.
The frog spoke up again and said, "If you kiss me, I'll turn back into a beautiful princess and stay with you for one week".
The engineer took the frog out of his pocket, smiled at it and returned it to the pocket.
The frog then cried out, "If you kiss me and turn me back into a princess, I'll stay with you for one week and do anything you want".
Again, the engineer took the frog out, smiled at it and put it back into his pocket.
Finally, the frog asked, "What is the matter? I've told you I'm a beautiful princess and that I'll stay with you for one week and do anything you want. Why won't you kiss me?"
The engineer said, "Look , I'm an engineer. I don't have time for a girlfriend, but a talking frog - now that's cool".