Wednesday, July 6, 2011

Subnetting for idiots. :)


SUBNETTING FOR IDIOTS

First of all I need you to get rid of all of the negative thoughts surrounding subnetting. Put down all of the books that you have read about the subject and navigate away from other sites claiming to provide an easy way to subnet. This technique requires no charts, just simply the know-how to work with the powers of 2.

We need to start with the fundamentals of IP addressing. An IP address is made up of 32 bits, split into 4 octets (Oct = 8, yes?). Some bits are reserved for identifying the network and the other bits are left to identify the host.

There are 3 main classes of IP address that we are concerned with.

Class A Range 0 - 127 in the first octet (0 and 127 are reserved)
Class B Range 128 - 191 in the first octet
Class C Range 192 - 223 in the first octet

Below shows you how, for each class, the address is split in terms of network (N) and host (H) portions.

NNNNNNNN. HHHHHHHH. HHHHHHHH. HHHHHHHH Class A
NNNNNNNN. NNNNNNNN. HHHHHHHH. HHHHHHHH Class B
NNNNNNNN. NNNNNNNN. NNNNNNNN. HHHHHHHH Class C

At each dot I like to think that there is a boundary; therefore there are boundaries after bits 8, 16, 24, and 32. This is an important concept to remember.

We will now look at typical questions that you may see on sub netting. More often than not they ask what a host range is for a specific address or which subnet a certain address is located on. I shall run through examples of each, for each class of IP address.

What subnet does 192.168.12.78/29 belong to?

You may wonder where to begin. Well to start with let's find the next boundary of this address.

Our mask is a /29. The next boundary is 32. So 32 - 29 = 3. Now 2^3 = 8 which gives us our block size i.e. 2 to the power of 3 equals 8.

We have borrowed from the last octet as the 29th bit is in the last octet. We start from zero and count up in our block size. Therefore it follows that the subnets are:-

192.168.12.0
192.168.12.8
192.168.12.16
192.168.12.24
192.168.12.32
192.168.12.40
192.168.12.48
192.168.12.56
192.168.12.64
192.168.12.72
192.168.12.80
.............etc.

Our address is 192.168.12.78 so it must sit on the 192.168.12.72 subnet.

What subnet does 172.16.116.4/19 sit on?

Our mask is /19 and our next boundary is 24. Therefore 24 - 19 = 5. The block size is 2^5 = 32.

We have borrowed into the third octet as bit 19 is in the third octet so we count up our block size in that octet. The subnets are:-

172.16.0.0
172.16.32.0
172.16.64.0
172.16.96.0
172.16.128.0
172.16.160.0
.............etc.

Our address is 172.16.116.4 so it must sit on the 172.16.96.0 subnet. Easy eh?

What subnet does 10.34.67.234/12 sit on?

Our mask is 12. Our next boundary is 16. Therefore; 16 - 12 = 4. 2^4 = 16 which gives us our block size.

We have borrowed from the second octet as bit 12 sits in the second octet so we count up the block size in that octet. The subnets are:-

10.0.0.0
10.16.0.0
10.32.0.0
10.48.0.0
.............etc.

Our address is 10.34.67.234 which must sit on the 10.32.0.0 subnet.

Hopefully the penny is starting to drop and you are slapping the side of your head realizing that you were a fool to think that sub netting was hard. We will now change the type of question so that we have to give a particular host range of a subnet.

What is the valid host range of the 4th subnet of 192.168.10.0/28?

Easy as pie! The block size is 16 since 32 - 28 = 4 and 2^4 = 16. We need to count up in the block size in the last octet as bit 28 is in the last octet.

192.168.10.0
192.168.10.16
192.168.10.32
192.168.10.48
192.168.10.64
.................etc.

Therefore the 4th subnet is 192.168.10.48 and the host range must be 192.168.10.49 to 192.168.10.62, remembering that the subnet and broadcast address cannot be used.

What is the valid host range of the 1st subnet of 172.16.0.0/17?

/17 tells us that the block size is 2^ (24-17) = 2^7 = 128. We are borrowing in the 3rd octet as bit 17 is in the 3rd octet. Our subnets are:-

172.16.0.0
172.16.128.0

The first subnet is 172.16.0.0 and the valid host range is 172.16.0.1 to 172.16.127.254. You must remember not to include the subnet address (172.16.0.0) and the broadcast address (172.16.127.255).

What is the valid host range of the 7th subnet of address 10.0.0.0/14?

The block size is 4, from 16 - 14 = 2 then 22 = 4. We are borrowing in the second octet so count in the block size from 0 seven times to get the seventh subnet.

The seventh subnet is 10.24.0.0. Our valid host range must be 10.24.0.1 to 10.27.255.254 again remembering not to include our subnet (10.24.0.0) and the broadcast address (10.27.255.255).

What if they give me the subnet mask in dotted decimal?

If you're lucky and they give you a mask in dotted decimal format then you should have an even easier time. All you need again is your block size.

Let's say they have given a mask of 255.255.255.248 and you wish to know the block size. Here's the technique:

1. Starting from the left of the mask find which is the first octet to NOT have 255 in it.
2. Subtract the number in that octet from 256 to get your block size e.g. above it is 256 - 248 = block size of 8.
3. Count up from zero in your block size in the octet identified in step 1 as you have learned above (the example above would be in the last octet).

Another example is a mask of 255.255.192.0 - you would simply count up in 256 - 192 = 64 in the third octet.

One more example is 255.224.0.0 - block size is 256 - 224 = 32 in the second octet.

What now?

Now it's time to go and pick up those books again and go straight to the practice questions, completely by-passing any of their techniques. Use my method and you will be laughing!




HA

Psych Study Guide part 2


Study Guide for Psych

1.      All thoughts and feelings we have when we are awake and reasonably alert are called Waking Consciousness

2.      Day dreaming, meditation, intoxication, sleep and hypnosis are all types of Altered State Of Consciousness.

3.      The altered state of consciousness that occurs without deliberate effort is Daydreaming.

4.      Apparently effortless shifts in attentions away from the here and now into a private world of make believe are DayDreams

5.      The naturally occurring chemical Adenosine appears to trigger sleepiness.


6.      A biological cycle or rhythm that is approximately 24 hours long is a Circadian cycle.

7.      The human biological clock is governed by a cluster of cells known as the Suprachiasmatic Nucleus.

8.      A hormone that peaks during the night and promotes sleep is Melatonin.

9.      Stage 1 sleep lasts for Only a Few Minutes.

10.   A night school student who falls asleep in class sleeps for about 10 minutes before his professor notices and tries to wake him. AT this point it is hard to awaken him and he does not readily respond to the teacher’s voice. A brain scan would show his brain producing long, slow brain waves but not delta waves. He is most likely in Stage 2 sleep.

11.   The initials REM stand for Rapid Eye Movement.

12.   Sleep deprivation is clearly linked to Depression in college students.

13.   A sleep disorder characterized by sudden nodding off during the day and loss of muscle tone following moments of emotional excitement is Narcolepsy.

14.   According to Freud, in sleep and dreams, people can express ideas free from Conscious Controls and Moral Rules.

15.   According to Freud, the visible or directly observable content of a dream is its Manifest content


16.  Chemical substance that changes peoples mood and perceptions are known as Psychoactive drugs

17.  Substance abuse is characterized by a pattern of repeated drug use that can lead to each of the following [sic] except The Development Of Tolerance to a Recreational Drug

18.  Unpleasant physical or psychological effects that follow the discontinuance of a dependence-producing substance is Withdrawal.

19.   To eliminate sources of error in drug research, the research uses The Double Line Procedure in their research.

20.  Research has found that every addictive drug causes Dopamine levels in the brain to increase

21.  Depressants are chemicals that retard behavior by either speeding up or slowing down nerve impulses.

22.  Addictive drugs such as heroine that dull the sense and induce feelings of euphoria, well-being and relaxation are Opiates.

23.  Drugs that activate the sympathetic nervous system and produce feelings of optimism and boundless energy are called Stimulants.

24.  Caffeine, Nicotine, Amphetamines and Cocaine are members of a class of drugs known as Stimulants.

25.  The most addictive and dangerous stimulant today is Nicotine.

26.  Amphetamines are Stimulants

27.  Any number of drugs such as LSD and Mescaline that distort visual and auditory perception are Hallucinogens.

28.   The active ingredient in marijuana is THC

29.  According to the Disease Model, alcoholism is not a moral issue but a medical one.

30.  Various methods of concentration, reflection or focusing of thoughts that reduce activity of the sympathetic nervous system are Meditations.

31.  The process by which experience or practice results in a relatively permanent change in behavior or potential behavior is known as Learning

32.  By pairing the ringing of a bell with the presentation of meat, Pavlov trained dogs to salivate to the sound of a bell even when no meat was presented. In this experiment, the presentation of the meat was the Unconditioned Stimulus.

33.  By pairing the ringing of a bell with the presentation of meat, Pavlov trained dogs to salivate to the sound of a bell even when no meat was presented. In this experiment the ringing of the bell was the Conditioned Stimulus.

34.  By pairing the ringing of a bell with the presentation of meat, Pavlov trained dogs to salivate to the sound of a bell even when no eat was presented. In this experiment, salivation to the meat was the Unconditioned Response.

35.  By pairing the ringing of a bell with the presentation of meat, Pavlov trained dogs to salivate to the sound of a bell even when no meat was presented. In this experiment, salivation to the bell was the Conditioned Response.

36.  Intense, irrational fears of particular things, activities or situation are calls Phobias.

37.  A kind of therapy closely related to classical conditioning that is designed to gradually reduce anxiety about a particular object or situation is known as Desensitization Therapy.

38.  Conditioned taste aversions are typically learned after Only One Pairing between the aversive food and the nauseous reaction to it.

39.  A child learned that whenever he eats all his dinner he gets a cookie for dessert. This type of learning is best explained by Operant Conditioning.

40.   Operant conditioning operates on the principle that behaviors occur more often when they are Reinforced.

41.  Any stimulus that follows a behavior and increases the likelihood that the behavior will be repeated is called a Reinforcer.

42.  Any stimulus that follows a behavior and decreases the likelihood that the behavior will be repeated is called a Punisher.

43.  A box used in operant conditioning of animals, which limits the available responses and thus increases the likelihood that the desired response will occur, is called a Skinner Box.
44.   A reinforcer that adds something rewarding to a situation is a Positive Reinforcer.

45.  A reinforce that removes something unpleasant from a situation is a Negative Reinforcer.

46.  Presenting an aversive stimulus to eliminate undesired behavior is an example of Punishment.

47.   A relationship in which one event depends on another is known as a Contingency.

48.   In classical conditioning, the most effective method is to present The CS Just Before The US.

49.   Scott works at a job where he is paid a salary every two weeks. Scott is being reinforced on a Fixed-Interval schedule.

50.   Lila doesn’t like her psychology class because the instructor uses unannounced “pop” exams to test the class. As a result, she never knows when she will be tested. Her instructor is testing her on a Variable-Interval schedule.

51.  Gambling behavior is very hard to extinguish because it is reinforced according to a Variable-Ratio schedule of reinforcement.

52.  A salesperson who gets an increase in salary for every 100 policies he or she sells is being reinforced according to a Fixed-Ratio schedule of reinforcement.

53.   In classical conditioning, extinction occurs because the CS is no longer paired with the US (CS;US)

54.  In operant conditioning, extinction occurs as a result of withholding Reinforcement.

55.   A person is conditioned to fear white rats. Soon after, she also begins to fear white cats, white dogs, and white rabbits. Her new unconditioned fears result from Stimulus Generalization.

56.  The process of learning to respond only to a single specific object or event and inhibit the response to all other stimuli is called Stimulus Discrimination

57.   A reinforce that is reinforcing in and of itself is called a Primary reinforcer
58.  A reinforce that takes on its reinforcing properties only through association with other reinforcers is called a Secondary Reinforcer.

59.  Money is a secondary reinforce.

60.  The view of learning that emphasizes the ability to learn by observing a model or receiving instructions without firsthand experience by the learner is called Social Learning Theory.

61.  A key to social learning theory is Observational Learning.

62.   In Bandura’s classic (1965) study of children exposed to a film of an adult hitting a Bobo doll, BOTH the children who saw the model rewarded and the children who saw the model punished Learned To Imitate The Adults Behavior Equally Well

63.   The study of psychological and physical changes from birth through old age is called Developmental.

64.  The period of developmental changes by evaluating the same people at different points in their lives is a Longitudinal Study

65.  The period of development from conception to birth is called the Prenatal Period

66.  From second week until the third month after conception, the developing organism is called an Embryo.

67.  From the third month after conception until birth, the developing organism is knows as a Fetus.

68.  Times when certain internal and external influences have a major impact on development, whereas at other times those same influences would have little impact are called Critical Periods.

69.   A condition characterized by facial deformities, heart defects, stunted growth and cognitive impairments is Fetal Alcohol Syndrome.

70.  In the United States each year about 100,000 miscarriages are caused by smoking

71.   Psychologists often use the term Temperament to refer to a newborn child’s personality.

72.   Human babies are born with their eyes Open And Functioning.

73.   The average ages which voluntary skills such as grasping, crawling and walking occur are known as Developmental Norms.

74.  The Correct order for Piaget’s four stages of cognitive development are, Sensory-Motor, Preoperational, Concrete-Operational, Formal-Operational.


75.  Piaget’s concept that things continue to exist even when they are out of sight is called Object Permanence.

76.  Being unable to see things from another’s point of view or put yourself in someone else’s place is known as Egocentrism.

77.  The mother of a young child who didn’t like to drink milk was trying to coax him to drink some. Taking a glass of milk, she poured it all into a smaller cup and said “There! Now you won’t have to drink so much.” This works because the child does not yet understand the principles of Conservation.

78.  Kohlberg theorized that as people develop, they mature through 3 stages of moral development.

79.   According to Kohlberg, children interpret behavior in terms of concrete consequences at the Preconventional level of moral development.

80.   A duckling hatches next to a small puppy. Since the puppy is the first thing seen by the duckling, it follows the puppy everywhere and seems to assume that the puppy is its mother. This is an example of Imprinting.

81.   The emotional bond formed during the first year of life that makes human babies cling to their caretakers is called Attachment.

82.  According to Baumrind’s research, authoritative parents are likely to have children who are Self-Reliant.

83.  Children between the ages of 1.5-2 years old often play together side by side, doing the same thing but not interacting much with each other. This process is known as Parallel Play.

84.  A network of same aged friends and acquaintances who give one another emotional and social support is known as a Peer Group.

85.   Both boys and girls usually develop a sense of gender identity by around age 3.

86.   General beliefs about characteristics that men and women are presumed to have are called Gender Stereotypes.

87.  The American Academy of pediatrics says that children under the age of two should Not Watch Any Television At All.

88.  The most obvious change ushering in adolescence is The Growth Spurt.
89.  The tendency of teenagers to feel that they are always “on stage” and are constantly being judged about their appearance and their behavior is known as the Imaginary Audience.

90.  The delusion that many adolescents that they are unique, very important and invulnerable is called the Personal Fable.

91.   In order to make the transition from dependence on parents to dependence upon one’s self, the adolescent must develop a stable sense of Identity.

92.   The period of intense self-examination and decision making that is part of the process of identity formation is called An Identity Crisis.

93.   More Females attempt suicide. More Males make successful attempts (Females;Males)
94.   Once children leave home, many parents find Renewed Marital Satisfaction.

95.   One Half of all marriages end in divorce.

96.   The fastest growing segment of the US population is comprised of People Over The Age Of 65.

97.   Most older people are Healthy, Productive and Able.

98.   The vast majority of older adults are Sexually Active And Orgasmic.

99.   A disorder common in late adulthood that is characterized by losses in memory and cognition and changes in personality and that is believed to be caused by deterioration of the brain’s structure and function is Alzheimer’s Disease.

100.                    The typical sequence of the five stages of dying postulated by Kubler-Ross is Denial, Anger, Bargaining, Depression, Acceptance (DABDA).