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Zorluk: OrtaTroubleshooting Routing, Default Gateways, and ACLs

A network administrator is troubleshooting an issue where an application host with IPv4 address 192.168.4.25/24192.168.4.25/24 cannot transmit HTTPS management data to a target server at 10.200.5.50/2410.200.5.50/24. Diagnostic tests reveal that the host can successfully ping its default gateway (192.168.4.1192.168.4.1), but a traceroute to 10.200.5.5010.200.5.50 stops at 192.168.4.1192.168.4.1. Inspecting the gateway router shows the following configuration details:

text
ip route 10.200.5.0 255.255.255.0 192.168.4.1
access-list 105 permit udp host 192.168.4.25 host 10.200.5.50 eq 514

Which TWO of the following factors explain why HTTPS traffic (TCP port 443) fails to reach the destination? (Select TWO.)

  1. The static route entry uses the gateway router's local LAN IP address as the next hop rather than the upstream router's IP address.Cevap
  2. The access control list lacks an explicit permit rule for TCP port 443, resulting in the traffic being blocked by the implicit deny.Cevap
  3. C
    The host IP address and its configured default gateway IP address reside on different usable subnets.
  4. D
    The destination IP address belongs to the same VLAN broadcast domain and must be reached via Layer 2 switching without routing.

Cevap

The routing failure occurs because the static route incorrectly references the local gateway's own interface IP address (192.168.4.1192.168.4.1) as the next hop, and the Access Control List lacks a permit statement for TCP port 443, causing HTTPS packets to be dropped by the ACL implicit deny.
The issue stems from two distinct network layer misconfigurations: first, pointing a static route next hop to the router's own inbound interface IP address prevents proper forwarding to the next router; second, ACL 105 only permits UDP port 514 traffic, meaning TCP port 443 traffic hits the implicit deny rule at the end of the ACL.

Adım Adım Çözüm

1
Analyze the static route statement: 'ip route 10.200.5.0 255.255.255.0 192.168.4.1'.
Identify that 192.168.4.1 is the router's local LAN interface address, which is invalid as a next hop for outgoing traffic.
Static routes must point to a remote next-hop IP address on an adjacent router interface or an egress interface identifier.
2
Analyze the Access Control List: 'access-list 105 permit udp host 192.168.4.25 host 10.200.5.50 eq 514'.
Determine that only UDP syslog traffic (port 514) is explicitly permitted.
Standard ACL processing matches top-down and drops unmatched traffic at the final implicit deny all statement, blocking TCP port 443 (HTTPS).

Anahtar Kavram

Troubleshooting Static Routes and ACL Rules
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