CCNA 2 - Chapitre 9

Le routeur est généralement utilisé pour effectuer la NAT dans un environnement d'entreprise. La NAT (Network Address Translation) permet de traduire les adresses IP d'un réseau local en une seule adresse IP publique, ce qui permet aux appareils du réseau local d'accéder à Internet. Le routeur est le périphérique réseau qui gère le trafic entre les réseaux locaux et Internet, et il est capable d'effectuer la traduction des adresses IP grâce à la fonctionnalité NAT.

Dynamic NAT permet au routeur de remplir la table de traduction à partir d'un pool d'adresses publiques uniques à mesure que les ordinateurs envoient des paquets via le routeur à Internet. Avec le Dynamic NAT, chaque ordinateur du réseau interne se voit attribuer une adresse IP publique unique à chaque fois qu'il se connecte à Internet, ce qui permet de conserver un certain niveau d'anonymat et de sécurité pour les utilisateurs du réseau interne.

La fonction principale de la fonction NAT est de conserver les adresses IPv4. Le Network Address Translation (NAT) est utilisé pour traduire les adresses IP privées en adresses IP publiques afin de permettre à plusieurs appareils d'accéder à Internet en utilisant une seule adresse IP publique. Cela permet de préserver les adresses IPv4 limitées et de prolonger leur utilisation.

The correct answer is "Router# show ip nat translations". This command is used to display the active Network Address Translation (NAT) translations on a router. It provides information about the source IP address, destination IP address, and the translated IP address for each active NAT translation. This command is useful for network administrators to monitor and troubleshoot NAT configurations on a router.

The main advantage of using the NAT function with port address translation is that it allows many internal hosts to share the same public IPv4 address. This is beneficial because it helps conserve the limited number of available public IPv4 addresses, as multiple internal devices can use a single public address for communication with external networks. This allows for more efficient allocation of IPv4 addresses and helps in overcoming the IPv4 address exhaustion problem.

The probable cause of the absence of address translation in the network is that the access-list 1 command is misconfigured.

La commande "ip nat inside source static tcp 192.168.10.2 80 209.165.200.223 8080" permet de lier l'adresse IP locale interne (192.168.10.2) et le port local (80) à l'adresse IP globale interne (209.165.200.223) et au port global spécifiés (8080). Cela permet la traduction d'adresse réseau (NAT) pour permettre aux périphériques externes d'accéder à un service spécifique hébergé sur le périphérique interne identifié par l'adresse IP locale et le port local.

The two advantages of the NAT function are that it allows for the conservation of public IP addresses and enhances the confidentiality and security of a network.

If dynamic NAT without overloading is used and there are only six available addresses in the NAT pool, the request sent to the server for the seventh user will fail. This is because there are not enough available addresses to assign to the seventh user, resulting in the request being unsuccessful.

Based on the displayed result, it can be inferred that PAT (Port Address Translation) using an external interface has been implemented. This type of NAT allows multiple private IP addresses to be translated into a single public IP address by using different port numbers to distinguish between the connections. This helps conserve public IP addresses and enables communication between multiple devices on a private network and the internet.

One of the disadvantages of NAT is that there is no end-to-end addressing. This means that the internal hosts must use a unique public IPv4 address for external communication. NAT translates these internal addresses to a single public address, which can lead to issues with certain applications or protocols that require end-to-end addressing. This limitation can affect the functionality and efficiency of the network.

Les adresses locales uniques permettent aux sites d'être combinés sans créer de conflits d'adresses. Cette caractéristique est importante car elle garantit la stabilité et la cohérence des adresses IP utilisées au sein d'un réseau. Ainsi, les adresses locales uniques facilitent la gestion des adresses IP et évitent les problèmes de duplication ou de conflits d'adresses qui pourraient perturber la communication et le fonctionnement du réseau.

The IP address 209.165.20.25 represents the external global address, as it does not fall within the private IP address ranges of 192.168.0.0/16 or 10.0.0.0/8. The other options are either private IP addresses (192.168.0.100 and 10.1.1.2) or a range of private IP addresses (10.1.1.0). Therefore, the correct answer is 209.165.20.25.

The given configuration shows the use of both static NAT (ip nat inside source static) and dynamic NAT (ip nat inside source list). However, the configuration does not provide any information about whether these NAT configurations are functioning correctly. Therefore, it is not possible to determine if both static NAT and dynamic NAT are working based on the given information.

The engineer used the "overload" option because the company has more private IP addresses than available public IP addresses. This option allows the router to map multiple private IP addresses to a single public IP address, thus allowing the company to use more private IP addresses than they have public IP addresses.

The correct answer is "Elle definit les adresses qui peuvent etre traduites" which translates to "It defines the addresses that can be translated." This means that the marquee command in the partial configuration information of a Cisco broadband router is used to specify the addresses that can undergo translation.

The correct answer is "Il s'agit d'un mécanisme temporaire destiné à faciliter la migration d'IPv4 à IPv6." This statement is correct because NAT for IPv6 is indeed a temporary mechanism designed to assist in the transition from IPv4 to IPv6. NAT allows devices using IPv6 to communicate with devices using IPv4 by translating the addresses between the two protocols. This helps to ensure compatibility and smooth transition during the migration process.

La NAT dynamique permet le mappage automatique des adresses IP locales internes avec les adresses globales internes. Cela signifie que lorsque les hôtes internes envoient des paquets à travers le réseau, la NAT dynamique modifie les adresses source des paquets en remplaçant l'adresse IP privée par une adresse IP publique. Cela permet aux hôtes internes d'accéder à Internet en utilisant une seule adresse IP publique, ce qui facilite la gestion des adresses IP et permet d'économiser des adresses IP publiques.

The correct answer is "R1(config)#ip nat inside source static tcp 192.168.5.25 8080 209.165.200.230 80". This command configures a static NAT translation on the router, mapping the internal IP address 192.168.5.25 and port 8080 to the external IP address 209.165.200.230 and port 80. This allows external users to access the web server without specifying the port number.

The correct answer is "Il utilise le numero de port TCP ou UDP de destination du paquet entrant" which means that a PAT-compatible router uses the destination TCP or UDP port number of the incoming packet to transfer it to the appropriate internal hosts.

The advantage of deploying NAT IPv4 technology for internal hosts of a company is that it provides flexibility in designing the IPv4 addressing scheme. This means that the company can use private IP addresses internally and translate them to public IP addresses when communicating with external networks. This allows for efficient use of IP addresses and simplifies network management.

The correct answer is "Le mappage d'addresses plusieurs-a-une entre adresses locales et globales". This type of Network Address Translation (NAT) is used when multiple local addresses are mapped to a single global address. In this scenario, the technician needs to configure the router to use different TCP port numbers for each internet access through a server. This requires mapping multiple local addresses to a single global address to ensure proper communication between the local network and the internet.

The command "ip nat pool" is used to define a pool of global IP addresses that can be used for dynamic NAT translation. These global IP addresses are assigned to internal hosts, allowing them to access external networks. This pool of global addresses is used to translate the internal IP addresses to external IP addresses when the internal hosts communicate with external networks. Therefore, the correct answer is "le pool d'adresses globales" which translates to "the pool of global addresses".

The probable cause for the client PC's inability to access the web server is that the interface s0/0/0 should be identified as the external NAT interface.

Les adresses ULA IPv6 ne sont pas routables sur Internet. Cela signifie qu'elles ne peuvent pas être utilisées pour communiquer directement avec des appareils ou des réseaux sur Internet. Elles sont destinées à être utilisées à l'intérieur d'un réseau privé, comme une entreprise ou une organisation, pour permettre la communication entre les appareils à l'intérieur de ce réseau. Cela garantit que les adresses ULA IPv6 ne sont pas utilisées en double sur Internet et permet de conserver l'espace d'adressage IPv6 pour les adresses qui doivent être routables sur Internet.

To make the given command "ip nat inside source list 4 pool corp" work, a numbered access control list (ACL) with the number 4 needs to be configured. This ACL should define the private IP addresses assigned by NAT. This means that the correct answer is "Une liste de contrôle d'accès portant le numéro 4 qui définit les adresses privées attribuées par la NAT."

To make the given command work, a NAT pool called "corp" needs to be configured. This pool defines the starting and ending public IP addresses. This means that the router will use this pool to translate the private IP addresses to public IP addresses when performing NAT.

The correct answer is that redirection allows an external user to access a service on a private IPv4 address within a LAN. This means that when a user outside of the LAN wants to access a specific service hosted on a private IP address within the LAN, redirection enables the user to reach that service by redirecting the incoming traffic to the appropriate internal IP address. This is commonly used in scenarios where a company or organization wants to provide access to certain services hosted on internal servers to external users.

The probable cause of the lack of connectivity between the web server and the users on the internet is that the NAT configuration on the router has an incorrect internal local address. This means that the router is not correctly translating the internal IP address of the web server to the external IP address that is visible on the internet. As a result, the users on the internet are unable to establish a connection with the web server.

The correct answer is to define a pool of global addresses to be used for translation in case of overload and to identify the internal interface. These are the steps required to configure Port Address Translation (PAT). The pool of global addresses is necessary to assign unique public IP addresses to the internal private IP addresses when they communicate with external networks. The identification of the internal interface is important to specify which interface will be used for the translation process.