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Zorluk: ZorInside Source NAT and PAT Configuration and Verification

An administrator notices that while the first host on the internal network (10.1.10.0/2410.1.10.0/24) can access the internet, subsequent hosts are unable to establish outbound connections simultaneously. Inspecting Router1 reveals the following running configuration:

text
access-list 105 permit ip 10.1.10.0 0.0.0.255 any
ip nat pool EDGE_POOL 203.0.113.5 203.0.113.5 prefix-length 32
ip nat inside source list 105 pool EDGE_POOL

Command output from `show ip nat statistics` confirms:
text
Total active translations: 1 (0 static, 1 dynamic, 0 extended)
Outside interfaces: GigabitEthernet0/1
Inside interfaces: GigabitEthernet0/0
Hits: 142 Misses: 18
Dynamic mappings:
-- Inside Source
access-list 105 pool EDGE_POOL ref count 1

Which configuration modification must be applied to Router1 to allow all internal hosts on the 10.1.10.0/2410.1.10.0/24 network to share the single IP address assigned to `EDGE_POOL` concurrently?

  1. Append the overload keyword to the statement: ip nat inside source list 105 pool EDGE_POOL overloadCevap
  2. B
    Modify the pool range in EDGE_POOL to include addresses from 172.16.0.0 to 172.35.255.255 to provide enough addresses for dynamic allocation
  3. C
    Replace the pool parameter with interface GigabitEthernet0/1 without additional keywords: ip nat inside source list 105 interface GigabitEthernet0/1
  4. D
    Add a deny entry for host traffic at the end of access-list 105 to prevent implicit deny behavior from blocking NAT translations

Cevap

Appending the overload keyword to the inside source NAT configuration command (ip nat inside source list 105 pool EDGE_POOL overload) enables Port Address Translation (PAT).
The configuration present on Router1 establishes standard dynamic 1-to-1 NAT. Because the pool contains only one IP address (203.0.113.5), only the first internal host receives a translation. Appending the overload keyword modifies the translation engine to perform Port Address Translation (PAT), allowing multiple inside local hosts to share a single inside global address by using unique transport-layer port numbers.

Adım Adım Çözüm

1
Analyze the configuration and verification output
The command 'ip nat inside source list 105 pool EDGE_POOL' without the overload keyword configures standard dynamic NAT. Because EDGE_POOL contains only a single IP address (203.0.113.5), only 1 dynamic translation entry (extended = 0) can exist at any given time.
Standard dynamic NAT allocates global IP addresses on a one-to-one basis. Once all pool addresses are exhausted, additional hosts attempting connection are dropped (misses increase).
2
Identify the missing component for port multiplexing
To allow multiple internal hosts to share one global IP address, Layer 4 port numbers must be tracked using Port Address Translation (PAT).
PAT requires the 'overload' keyword at the end of the 'ip nat inside source' command.
3
Formulate the correct configuration command
Execute 'ip nat inside source list 105 pool EDGE_POOL overload' on Router1.
This enables extended translations, allowing thousands of concurrent internal sockets to multiplex over port numbers assigned to 203.0.113.5.

Anahtar Kavram

Port Address Translation (PAT) Overload Keyword Requirement
Tahmini Süre:2m 0s
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Inside Source NAT and PAT Configuration and Verification

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