Flashcards
CCNA2: NAT
Flashcards do conjunto (35)
- 1What is the private address spaces?10.0.0.0/8
172.16.0.0/12
192.168.0.0/16 - 2What is the two main purposes of NAT-Translate network IPv4 address
-Conserve public IPv4 addresses - 3Where is NAT usually configured?At a border router for a stub network
- 4What is an inide local address?source host address seen from inside the network
- 5What is the inside global address?soure host address seen from outside the network
- 6What is the outside global addressdestination host address seen from outside its network
- 7What is the outside local addressdestination host address seen from inside its network
- 8Define Static NAT-one-to-one mapping of local and global addresses
-Configured manually - 9Define Dynamic NAT-Uses pool of public addresses
-Assigns on first-come-first served basis
-Requires enough addresses for total number of simultaneous user sessions - 10Define 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 - 11Advantages of NAT-Conserves legally registered addressing scehme
-Increases flexibility of connections
-Provides consistency for internal network schemes
-Provides some networ security - 12Disadvantages of NAT-Peformance is degraded
-End-to-end functionality is degraded
-End-to-end IP traceability is lost
-Tunneling is more complicated - 13When connecting to an ISP does NAT translate to public or private address?Can be both depending on setup
- 14Give a situation where static NAT is particulary usefulWeb servers
- 15What type of NAT does most home routers use?PAT
- 16What does NAT use for the session identifier for ICMP echo requestQuery ID
- 17Define the concept of Next Avaliable portIf NAT already has a mapping using the same port number if an incoming translation - it will use the next avaliable number
- 18Is it required NAT supports specific protocols if a Layer 4 segment is not present (TCP/UDP)Yes
- 19How 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) - 20How does NAT increase the flexibility of connections to the public network-Multiple pools
-Backup pools
-Load balancing pools - 21Should NAT be used to provide security?No - a stateful firewall should
- 22What protocol is specificly affected by the peformance degregation of NAT?VOiP
- 23With NAT the first packet is always ________ switchedProcess (swiched)
- 24Do some protocols rely on end-to-end addressing. Which?Yes. Usually affects security protocols - eg tunneling protocols such as IPSec, L2TP and PPTP
- 25How does NAT affect troubleshooting?Makes it difficult to trace packets and determine cause of problems
- 26How does NAT affect tunneling protocols?Modifies value in the header - causes integrity tests to fail
- 27What are three commands used to verify NATshow ip nat translations
show ip nat statistics
debug ip nat - 28What 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 - 29Where is port forwarding neccasaryOn border gateway routers which use PAT - as there is no mapping between port numbers and inside local address to forward top
- 30Does IPv6 have NAT?Yes and No. It has a NAT which translates IPv6 to IPv4 but no IPv6 ULA to IPv6 global unicast
- 31What 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 - 32Prefix of an IPv6 unique local addressFC00::/7
- 33What is NAT64Translate IPv4 packets to IPv6 packets
- 34Which is NAT-PT?IPv4 to IPv6 translation protocol that was depreated and has been replaced by NAT64
- 35—