C’est quoi un serveur DNS et quel en est son rôle ?
Nous allons aborder ici un serveur dont le rôle est essentiel dans Internet, je veux parler bien évidemment du serveur DNS. Vous verrez qu’il est utilisé partout sans forcément que vous vous en rendiez compte.Comme d’habitude pas de termes trop compliqués, je vais vous donner une définition du DNS expliquée de façon simple et répondre aux questions : « C’est quoi un serveur DNS et quel est son rôle ? ». Et pour terminer, nous aborderons également le lien avec le domaine.
Définition et rôle du DNS
Tout d’abord : DNS veut dire « Domain Name System » ou système de nom de domaine. Je vais tout d’abord vous expliquer le fonctionnement, puis nous aborderons la notion de nom de domaine (ou de sous-domaine).
Pour vous expliquer, le rôle et le fonctionnement d’un serveur DNS, je vais reprendre l’exemple du téléphone.
Vous souhaitez appeler quelqu’un dont vous ne connaissez pas le n° de téléphone ?
Que faites-vous ? ….
…. vous utilisez un annuaire !
Et bien voila, un serveur DNS est un annuaire pour ordinateur. Lorsque vous voulez accéder à un ordinateur dans le réseau, votre ordinateur va interroger le serveur DNS pour récupérer l’adresse de l’ordinateur que vous voulez joindre. Une fois, que votre ordinateur aura récupéré l’adresse du destinataire, il pourra le joindre directement avec son adresse IP.
Le serveur DNS va permettre de faire la relation entre nom d’ordinateur et adresse IP. (ramené au téléphone, on obtient : nom de l’abonné et n°).
Vous allez me dire :
» mais je ne cherche jamais à joindre un ordinateur dans le réseau ! «
A quoi, je vais vous répondre :
» bien sur que si ! «
» Actuellement vous lisez ces lignes qui ne sont stockés pas sur votre ordinateur, donc votre ordinateur s’est connecté à un serveur pour récupérer les pages qui sont affichées sur votre écran. «
Exemple
Reprenons en modèle ce que vous avez fait pour arriver sur cette page, et regardons comment le serveur DNS est intervenu sans que vous le sachiez.
Vous avez lancé votre navigateur Internet et vous avez « www.google.fr » comme moteur de recherche par défaut. Donc la page google s’est affichée. Voici le mécanisme complet et regardez à quel endroit le serveur DNS est appelé.
Dans l’exemple ci-dessus, on voit que la requête « quelle est l’adresse de www.google.fr » a répondu 74.125.230.248. Cette requête s’appelle une résolution de nom de domaine.
Si l’on poursuit, on peut constater que le serveur DNS n’est utilisé que sur la partie 1-Question et 2-Réponse. Une fois que l’ordinateur a récupéré l’adresse du serveur à joindre, il n’a plus besoin du serveur DNS.
Cette adresse IP n’est pas une adresse au hasard. Elle correspond bien à un des serveurs de Google. (il y en a évidemment un grand nombre). Donc, si dans votre dans la barre d’adresse de votre navigateur, vous tapez : http://74.125.230.248, la page de recherche de Google doit s’afficher.
Attention, cela fonctionne à l’heure ou j’écris ces lignes, mais ce ne sera peut-être pas le cas au moment ou vous les lirez. (le serveur 74.125.230.248 sera peut-être éteint ? ou affecté à de nouvelle tâches ?)
Pour faire le test vous cliquer sur : http://74.125.230.248
NB du 05/01/2016 : Comme je vous le disais au-dessus, l’adresse peut avoir changé, et c’est le cas : Essayez maintenant avec http://74.125.206.94
Et chez moi ?
La plupart des personnes ignorent cette notion est c’est bien compréhensible. Alors comment cela peut-il fonctionner chez moi puisque je n’ai jamais renseigné ces serveurs ?
Les serveurs DNS fonctionnent en cascade. Pour expliquer cela on pourrait dire que lorsque qu’un serveur ne connait pas la réponse, il va demander à son « parent »
Chez vous, le serveur DNS est votre box (sauf si vous avez renseigné autre chose), et si votre box ne sait pas répondre, elle va interroger son parent : le(s) serveur(s) DNS de votre fournisseur d’accès. Cela peut remonter comme ça jusqu’aux serveurs racines. (on va dire pour simplifier que les serveurs DNS racines sont les serveurs de base du système : on ne peut pas remonter plus haut.)
La configuration DNS de votre ordinateur (ou tablette, et tout autre équipement connecté chez vous) est fournie par le serveur DHCP.
Un fichier
Peut-être en entendrez vous parler si vous travaillez dans l’informatique (ou si vous bricolez un peu). Un fichier présent sur la machine peut remplacer les requêtes DNS.
Ce fichier est le fichier « host » (hôte en français). Il va contenir la correspondance entre les adresses demandées et les adresses IP. Sur chaque ligne de ce fichier on va retrouver au début l’adresse IP suivi d’un espace ou d’une tabulation et ensuite du ou des nom(s) correspondant à cette adresse. Exemple : 74.125.230.248 www.google.fr
La sécurité
Parlons juste un peu de sécurité.
Pour bien comprendre de quoi je veux parler, je vais reprendre l’exemple du téléphone :
Imaginez que vous ayez entre les mains un faux annuaire (piraté) ou les numéros de téléphone ne soient pas les bons, et vous renvoie vers des pirates.
Vous ayez besoin d’appeler votre banque : Vous appelez le numéro de téléphone et vous allez forcément tomber sur des pirates (mais vous ne le savez pas).
Au bout du fil, on peut vous demander des informations confidentielles, et vous les donnerez en tout confiance !!!
Il faut bien comprendre que cela peut être pareil avec des serveurs DNS et qu’il existe des virus qui modifie vos paramètres réseaux ou votre fichier « hosts » pour faire pointer les requêtes DNS vers des serveurs pirates.
Une des blagues des administrateurs réseaux est de modifier, au sein de l’entreprise, une des entrées DNS d’un site vers un autre site. (Par exemple : faire pointer Facebook vers le site des Tortues Ninja ! : ainsi chaque fois que quelqu’un voudra aller sur Facebook, il se retrouvera sur le site des Tortues Ninja)
Changer de DNS
Sachez qu’il est tout à fait possible de changer de DNS. Lorsque vous utilisez votre connexion Internet, les adresses des serveurs DNS sont généralement ceux de votre FAI, mais sachez qu’il est possible d’en changer. Vous trouverez ci-dessous des sites proposant des listes de serveurs :
et je peux également vous en donner 2 très connus :
OpenDNS : 208.67.220.222 et 208.67.222.220
Google : 8.8.8.8 et 8.8.4.4
Pourquoi changer de DNS ?
Je vois 2 raisons principales pour changer de DNS :
Si vous avez peur d’être « espionné », (car un serveur DNS) sait exactement quels sites vous consultez, mais il peut également vous renvoyer vers les sites qu’il a choisi.
Si vous trouvez votre accès un peu lent, (car rappelez-vous un serveur DNS est appelé à chaque page consultée) et plus il mettra du temps à répondre, plus la page mettra du temps à s’afficher.
Nous utilisons les cookies afin d'améliorer votre expérience sur notre site Web ainsi que pour la publicité. Vous pouvez gérer vos préférences actuelles en cliquant sur le bouton "Réglage"
Lire notre politique de cookies
vous avez une question particulière à laquelle nous n'avons pas répondu ?
Posez-là nous ici !
You can invite several close friends to communicate on a daily basis in the same group chat, without any restrictions on speech.Its aura is far inferior to the ones Li Shiming used back then.
Second senior brother, you are really ruthless. You are going to take all three places Third senior brother Lu Shi shouted dissatisfied.Just now, his spiritual thoughts had been placed on the Sword Intent Buddha Bead.
bowed and said. He is very clear about his position in his heart.There are many talented monks, and several can be found in every Immortal Ascension Conference, but there are not many talented monks who can truly grow up.
The monk s promise was very Safety Considerations and Possible Side Effects prudent, and Li Shiming s acceptance represented a responsibility.He took out the Soul Gathering Disk from the machine room.
In this way, in theory, as long as he is fast enough, he can make the monks following him lose the ability to lock on his breath.This secret method was to use spiritual stones to hit people.
If there was an alchemist in front of him Hydroxycut Non-Stimulant Weight Loss Mixed Fruit Gummies who had been immersed in alchemy for decades, Master Ma would at most praise him for his talent.Calm down Li Shiming suppressed the panic in his heart, and his brain continuously exchanged information with IBMz15 to analyze and judge the situation on the battlefield.
Li Shiming nodded, indicating that this was indeed the case.Li Yuanba knew not to give Ren Pengxiao a chance, so he inspired the secret technique of Portion Control and Mindful Eating Shifang Sword Cultivation.
He caught two small fish from the spiritual spring, made a pot of fish soup with the spiritual spring water, added spiritual rice, and had a delicious meal.This farmland is a low lying land, about ten acres in size, surrounded by large and small rocks.
The first batch of wafers was produced. Due to technical and experience reasons, he was not satisfied with the batch of wafers.He came here this time just for the corpse refining monk.
You must know that most of the spiritual power and spirit of a golden elixir monk is concentrated inside the golden elixir, and the golden elixir is the source of power for the golden elixir monk.Take the two body training techniques practiced by Li Shiming as an example.
Li Shiming s expulsion technique was activated, and a spiritual hand grabbed the paper.The Hao family made a big mistake some time ago, losing two monks, The Return to Whole Foods which caused the Hao family s strength to drop drastically.
As the Xuanming Sect s Qi Refining monks approached, he felt that he was being held up by Benefits of Weight Loss Gummies a spiritual force, and Frequently Asked Questions (FAQs) the water around his body was being excluded.Qiutan replied that the supplies he ordered would take twenty days to be delivered.
There is a chessboard on the table with Kelly’s Weight Loss Journey two boxes of black and white stones.He exchanged the first one for Ren Fei er. I chose the jade flying boat because it has better concealment effect when flying above the sea.
The value of the second grade Millennium Cold Crystal is indeed not Benefits of the ACV Keto Diet taken seriously by the Golden Core cultivators.Although it is a junior Ling Zhifu s spell and has not been advanced, when he cast it in the middle stage of Qi Refining, its power and flexibility have been greatly enhanced.
The other end of the copper wire was put into the computer room and connected to the output of the Q: How long does it take to see results with semaglutide? uninterruptible power supply.The spirit gathering disk gathers the spiritual energy in the void and wraps the clone in it.
This is why Elder Jian, after seeing Li Yuanba, did a little research and issued an assessment task.Help me The seventh level Qi Refining monk called out for help.
Through his spiritual sense, he could sense that the two monks were at the seventh level of Staying Motivated and Focused on Health Goals Qi refining.As long as Yun Where to buy Keto One ACV Gummies? Xingyi really dies, then the main spirit can definitely devour his soul, which can confirm that the other party s death is real.
If he hadn t used Magic Sound in the Ears Fake to influence them, this battle would still be a lot of trouble.Li Shiming decided to join a research project later, that is, how to transform the bronze corpse Benefits of ACV Gummies with K3 Spark Mineral to make it more powerful.
The differentiated sword light has limited damage to enemies of similar strength Health Benefits of ACV Gummies to itself.It s a pity that he didn t cultivate this bronze corpse from scratch.
If the Jindan cultivators were not discovered within two hundred miles of the sect s formation, then the Tianhai Sect would no longer have to mess around.The computer room space also Finding Community and Support needs aura. The richer the aura, the better it is for the growth of spiritual plants.
After the blessing of The First Appearance of Buddha s Light , its power has been somewhat improved.He skipped the black flag and continued to check the next item.
Secondly, Peak Recipe 4: Salad with Chicken and Avocado Master Zhao was afraid. Li Shiming s background was beyond imagination, which made Peak Master Zhao shrink back.The destruction of the magic weapon connected to one s own aura is almost equivalent to the severe damage suffered by the golden elixir monk.
You must know that Elder Baili personally investigated Qiutan on Nuu3 Gummies at Walmart Changming Island, and sensed the imprint left by Baili Jinyan from Qiutan and two assistants.Yin Shilan s figure disappeared for a moment, and then appeared in her original position.
It took N years to pour a large amount of magic into the world, saving himself some complicated steps.only then can we learn that there is no difference between the Lord of faith Common Myths About Trisha Yearwood Weight Loss and the wizard who is promoted as the incarnation of evil, High-Intensity Interval Training (HIIT) and we can still have unshakable faith
Ella s brainwashing ability is a bit too scary Facing the mocking words of Role of Medical Supervision in Adjusting Dosage Lin En and others, Joshua refused to listen, hear, speak, or speak
His whole body returned to the way it was before they came in, as if he was dead.
Linn knew very well that although they now relied on absolute force and sufficient material supplies to suppress most of the conflicts.This mysterious calmness also made Ankara, the God of Lies, somewhat hesitant, even slowing down his forward movements
But in the end, he could not hold back his desire for godhood and priesthood.
When he walked out of the examination room, Monroe couldn t help How Does Ketosium XS Keto Work? but break out in a cold sweat.The pointer rotated in a circle, and finally pointed to a mansion in the village.
The war legions that originally had high morale were torn in How to Choose the Right Weight Loss Clinic half from the center by the surging atmospheric waves.Based on all the novel things they saw after entering this city of fire and oil, Understanding Noom Weight Loss they didn t have many doubts about the contents of the periodic table of elements before.
This was completely inconsistent with the three ring wizard written in the intelligence Although there seems to be only one ring difference between the third ring and the fourth ring, their combat power is vastly different Fight There was no fear on Ivina s face.Everyone present was shocked. For Common Mistakes to Avoid When Using the Coffee Method the first time, someone forcibly resisted the attack Introduction to Ethan Suplee’s Weight Loss Journey of a nuclear explosion Sure enough, after the light beam dissipated, Ella s figure was not damaged at all, The Benefits of Original Keto Gummies and then she took one step forward and arrived in front of Lin En.
Some people make great progress all the way, but they are in high positions but cannot bear the entreaties of their relatives, and frequently act nepotistically and use power.Cord knew very well that if they lost the advantage of high speed flight, the possibility of escaping back to the Broken City would be almost zero Burn Weight Loss Pills: A Fiery Approach to Shedding Pounds Reviewed Fortunately, at this moment, a bright laser beam flew over from a distance, cutting off the sharp claws of the legendary beast, and then everyone saw a silver eagle flying past the middle.
Anthony kept pacing in the laboratory, thinking about what went wrong with his photoelectric effect and why the light beam could not produce a surrounding magnetic field.Susan and others also had astonished Staying Motivated Throughout Your Journey expressions on their faces, almost in disbelief.
The frightened Code sent out an electromagnetic wave to express his gratitude, repaired the damaged alchemy Benefits of Super Keto Gummies protection in the external field, and then relaxed Exploring the Hype: Reviews and Testimonials of Nova Optimal ACV Keto Gummies slightly with his heart in his throat.Lin En continued to explain. Without an inertial reference frame, it makes no sense to distinguish up, down, left, right, east, west, and south.
But once it weakens, these problems will erupt again So no matter how the priests and bishops tried to explain themselves, they could not reverse the ironclad fact that the crusade was defeated one after another in the kingdom They broke the myth of the invincibility of the Holy See End of Chapter The power of the Holy See has been rooted in this continent for a long time, and it is not easy to completely eliminate it.
The relationship between the The Landscape of Weight Loss in Chicago two is like the magnetic field and the electric field Just like the electric lamps all over the city of kerosene, after the electricity enters the wick, It is consumed in the form of light, or in other words, the electricity is converted into light and emitted If my guess is not wrong, electricity can be converted into light, and then the gathered light beam can also be converted into light.
The lance blessed with magic struck the armored vehicle at high speed, only making a small dent, and then the huge reaction followed the curve.The chaos in the northern part of the kingdom must Lose 10 Pounds in a Week: Top Methods for Quick Results be How much weight did Adele lose in 2025? dealt with as soon as possible The sooner the better Every named evil god has a legendary level of strength.
After a while, there was no Lean Keto: Revolutionizing Weight Loss on Shark Tank way to break through the armor s protection.The cylindrical cannons mounted on both sides of the wing immediately erupted, and a continuous barrage of barrages flew towards them.
Sanchez also realized that his words might cause some misunderstandings, so he quickly shook his head and said.The most important thing is that it is more Kevin James’ Exercise Routine for Weight Loss cost Challenges Faced at the Beginning effective to sell the grain to the parliament on the spot than for the grain merchants to risk being caught and smuggle the grain into the empire.
Bohr also said with appreciation. Indeed, the power possessed by that false god completely exceeded our expectations.
Return your own things. You bastard, hand over your things, you dare to rob my Xiliang Wang family s things Wang Shicang was furious.He sees the struggle between the forces very clearly and can t help but explain.
Then what should we do next Someone from Jiang Tianlong s capable general asked carefully.You don t need to ask anymore about this. It may be the place where Mount Tai is enshrined in Zen, or it may be the place where immortals are buried in Kunlun, or it may be the place where the stars of Emei are scattered.
Put in the big drum grass first. This big drum air contains rich infuriating energy and is the main raw material for replenishing qi.The identity of the alchemist really aroused The Benefits of ACV Gummies for Women the interest of Mr.
That kind of contained anger, Extremely scary. Stab At this moment, Ye Fei s palm was like a hook, and he pulled off a large piece of Zi Xiaoyu s dress.Ahem, Marshal Jiang
Seeing Jiang Longtian showing off his power, the provincial governor stepped forward, but was glared back by Jiang Tianlong.
As Chen Mohan said, many of these disciples and elders were killed by one blow, and some were directly shocked to death by powerful internal forces.However, she was extremely powerful after all, and she also seriously injured two people.
