14143141
Description
Flashcards by Sam Thomas, updated more than 1 year ago
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Created by Sam Thomas
almost 6 years ago
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| Question | Answer |
| What is the private address spaces? | 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 |
| What is the two main purposes of NAT | -Translate network IPv4 address -Conserve public IPv4 addresses |
| Where is NAT usually configured? | At a border router for a stub network |
| What is an inide local address? | source host address seen from inside the network |
| What is the inside global address? | soure host address seen from outside the network |
| What is the outside global address | destination host address seen from outside its network |
| What is the outside local address | destination host address seen from inside its network |
| Define Static NAT | -one-to-one mapping of local and global addresses -Configured manually |
| Define Dynamic NAT | -Uses pool of public addresses -Assigns on first-come-first served basis -Requires enough addresses for total number of simultaneous user sessions |
| Define Port Address Translation | -maps multiple private addresses to single or few public addresses -NAT overload -Validates incoming packets were requested -uses port number (for TCP/UDP) and other identifiers for other protocols -required PAT to support protocols |
| Advantages of NAT | -Conserves legally registered addressing scehme -Increases flexibility of connections -Provides consistency for internal network schemes -Provides some networ security |
| Disadvantages of NAT | -Peformance is degraded -End-to-end functionality is degraded -End-to-end IP traceability is lost -Tunneling is more complicated |
| When connecting to an ISP does NAT translate to public or private address? | Can be both depending on setup |
| Give a situation where static NAT is particulary useful | Web servers |
| What type of NAT does most home routers use? | PAT |
| What does NAT use for the session identifier for ICMP echo request | Query ID |
| Define the concept of Next Avaliable port | If NAT already has a mapping using the same port number if an incoming translation - it will use the next avaliable number |
| Is it required NAT supports specific protocols if a Layer 4 segment is not present (TCP/UDP) | Yes |
| How does NAT conerve the legally registered addressng scheme - what does this mean? | Allowing the privization of intranets Means that private addresses can be used for internal networks but when these networks want to communicate externally only a very small amount of addresses are neccasary (PAT) |
| How does NAT increase the flexibility of connections to the public network | -Multiple pools -Backup pools -Load balancing pools |
| Should NAT be used to provide security? | No - a stateful firewall should |
| What protocol is specificly affected by the peformance degregation of NAT? | VOiP |
| With NAT the first packet is always ________ switched | Process (swiched) |
| Do some protocols rely on end-to-end addressing. Which? | Yes. Usually affects security protocols - eg tunneling protocols such as IPSec, L2TP and PPTP |
| How does NAT affect troubleshooting? | Makes it difficult to trace packets and determine cause of problems |
| How does NAT affect tunneling protocols? | Modifies value in the header - causes integrity tests to fail |
| What are three commands used to verify NAT | show ip nat translations show ip nat statistics debug ip nat |
| What is port forwarding? | Act of forwarding a network port from one network node to another Packet sent to public IP address can be forwarded to private IP addresses |
| Where is port forwarding neccasary | On border gateway routers which use PAT - as there is no mapping between port numbers and inside local address to forward top |
| Does IPv6 have NAT? | Yes and No. It has a NAT which translates IPv6 to IPv4 but no IPv6 ULA to IPv6 global unicast |
| What is IPv6s form of private addresses? How are they used? | Unique local address Allow IPv6 communications across a local site Cannot be translated to global unicast |
| Prefix of an IPv6 unique local address | FC00::/7 |
| What is NAT64 | Translate IPv4 packets to IPv6 packets |
| Which is NAT-PT? | IPv4 to IPv6 translation protocol that was depreated and has been replaced by NAT64 |
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