Inspect configured NETCONF service, destination port and initial hello response. This investigation primarily applies to NETCONF over SSH port, not the current Proxy authentication failure for API caller problem. Prioritize: Inspect proxy env variables, proxy response headers and CONNECT trace.

Inspect listener ports, ACL hit logs and SSH handshake results. This investigation primarily applies to SSH versus Telnet management port, not the current Proxy authentication failure for API caller problem. Prioritize: Inspect proxy env variables, proxy response headers and CONNECT trace.

Inspect route entries, subnet masks and the exact destination IP in forwarding output. This investigation primarily applies to Find matching route using longest prefix, not the current Proxy authentication failure for API caller problem. Prioritize: Inspect proxy env variables, proxy response headers and CONNECT trace.

Configure approved source NAT for outbound flows and ensure stateful return traffic follows the mapping. This instead targets the different case NAT source translation to public Internet. The described VPN route missing for private API requirement specifically calls for Install or advertise the correct approved split-tunnel route and validate return reachability.

Calculate the network, usable host range and broadcast address before allocating from the prefix. This instead targets the different case Prefix mask calculation for API inventory. The described VPN route missing for private API requirement specifically calls for Install or advertise the correct approved split-tunnel route and validate return reachability.

Configure health-aware load balancing to stop routing new connections to unhealthy backends. This instead targets the different case Load balancer health checks after node failure. The described VPN route missing for private API requirement specifically calls for Install or advertise the correct approved split-tunnel route and validate return reachability.

The provider reaches the receiver over a valid TLS connection without downgrading to HTTP. That observation could confirm HTTPS service versus HTTP port, not the current VPN route missing for private API case. For this case, the decisive observation is: Traceroute to 10.80.5.20 uses the VPN tunnel and the API connects without public routing.

Tagged VLAN 210 traffic traverses the uplink and reaches the correct broadcast domain. That observation could confirm VLAN trunk allowed-list mismatch, not the current VPN route missing for private API case. For this case, the decisive observation is: Traceroute to 10.80.5.20 uses the VPN tunnel and the API connects without public routing.

Interactive command response correlates with RTT while bulk throughput remains adequate. That observation could confirm Latency versus throughput for interactive CLI, not the current VPN route missing for private API case. For this case, the decisive observation is: Traceroute to 10.80.5.20 uses the VPN tunnel and the API connects without public routing.

NAT maps private address/port tuples to routable external identities with state for replies. This relates to NAT source translation to public Internet. In the current VPN route missing for private API case the operative principle is: VPN traffic steering requires routes for private prefixes as well as tunnel authentication.

DHCP provides IP configuration while DNS resolves names; a link-local address signals DHCP failure in typical IPv4 clients. This relates to DHCP scope versus DNS resolution. In the current VPN route missing for private API case the operative principle is: VPN traffic steering requires routes for private prefixes as well as tunnel authentication.

SSH commonly uses TCP 22 and encrypts remote administration; Telnet commonly uses TCP 23 without encryption. This relates to SSH versus Telnet management port. In the current VPN route missing for private API case the operative principle is: VPN traffic steering requires routes for private prefixes as well as tunnel authentication.

Disabling one backend does not selectively block malicious source addresses. This risk occurs in the different Choose firewall rather than load balancer for deny policy situation. For the given VPN route missing for private API requirement, the directly relevant risk is: Successful VPN login alone does not make every private subnet reachable.

Changing the PC access VLAN will not fix an established path as far as R1. This risk occurs in the different Interpret two-router topology with blocked path situation. For the given VPN route missing for private API requirement, the directly relevant risk is: Successful VPN login alone does not make every private subnet reachable.

Choosing a broad aggregate over a valid more specific route can misdirect traffic. This risk occurs in the different Find matching route using longest prefix situation. For the given VPN route missing for private API requirement, the directly relevant risk is: Successful VPN login alone does not make every private subnet reachable.

Inspect SVI/gateway interfaces, routes and ACL or firewall policy. This investigation primarily applies to Select router for inter-VLAN reachability, not the current VPN route missing for private API problem. Prioritize: Inspect client route table, tunnel policy and firewall return path.

Inspect route entries, subnet masks and the exact destination IP in forwarding output. This investigation primarily applies to Find matching route using longest prefix, not the current VPN route missing for private API problem. Prioritize: Inspect client route table, tunnel policy and firewall return path.

Inspect interface drops, jitter, RTT and QoS class counters at each WAN hop. This investigation primarily applies to Packet loss and jitter for voice API alerts, not the current VPN route missing for private API problem. Prioritize: Inspect client route table, tunnel policy and firewall return path.

Keep client ingress limited to proxy 443 and permit proxy-to-backend 8080 only on the internal path. This instead targets the different case Identify reverse-proxy port in service path. The described Blocked transport port on correct host requirement specifically calls for Permit the specific authorized TCP 8443 flow on the intervening security path.

Restrict the management plane to an approved operations network and authenticated administrative roles. This instead targets the different case Management-plane isolation for API access. The described Blocked transport port on correct host requirement specifically calls for Permit the specific authorized TCP 8443 flow on the intervening security path.

Provide a Layer 3 gateway or suitable routing switch interfaces and inter-VLAN policy enforcement. This instead targets the different case Select router for inter-VLAN reachability. The described Blocked transport port on correct host requirement specifically calls for Permit the specific authorized TCP 8443 flow on the intervening security path.

Authorized SSH sessions work and TCP 23 is not reachable from unapproved networks. That observation could confirm SSH versus Telnet management port, not the current Blocked transport port on correct host case. For this case, the decisive observation is: A TCP handshake and authenticated application request succeed while other ports stay restricted.

The allocated host falls between .65 and .94 and excludes the network and broadcast addresses. That observation could confirm Prefix mask calculation for API inventory, not the current Blocked transport port on correct host case. For this case, the decisive observation is: A TCP handshake and authenticated application request succeed while other ports stay restricted.

An external test sees the translated public source and return packets reach the original private host. That observation could confirm NAT source translation to public Internet, not the current Blocked transport port on correct host case. For this case, the decisive observation is: A TCP handshake and authenticated application request succeed while other ports stay restricted.

A load balancer distributes connections according to health and service selection policy. This relates to Load balancer health checks after node failure. In the current Blocked transport port on correct host case the operative principle is: IP reachability and ICMP success do not prove access to a separate TCP service port.

Real-time traffic quality depends on delay variation and loss, not merely link nominal capacity. This relates to Packet loss and jitter for voice API alerts. In the current Blocked transport port on correct host case the operative principle is: IP reachability and ICMP success do not prove access to a separate TCP service port.

The control plane computes paths while the data plane forwards packets using installed forwarding entries. This relates to Control plane BGP convergence versus data plane. In the current Blocked transport port on correct host case the operative principle is: IP reachability and ICMP success do not prove access to a separate TCP service port.

Changing the PC access VLAN will not fix an established path as far as R1. This risk occurs in the different Interpret two-router topology with blocked path situation. For the given Blocked transport port on correct host requirement, the directly relevant risk is: Changing DNS will not fix an ACL blocking the correct host and port.

Inaccurate clocks can misorder incidents even when interface counters are correct. This risk occurs in the different NTP and SNMP roles during incident analysis situation. For the given Blocked transport port on correct host requirement, the directly relevant risk is: Changing DNS will not fix an ACL blocking the correct host and port.

Without a default route, destinations outside connected networks cannot be reached normally. This risk occurs in the different Gateway required for remote subnet situation. For the given Blocked transport port on correct host requirement, the directly relevant risk is: Changing DNS will not fix an ACL blocking the correct host and port.

Inspect SVI/gateway interfaces, routes and ACL or firewall policy. This investigation primarily applies to Select router for inter-VLAN reachability, not the current Blocked transport port on correct host problem. Prioritize: Inspect SYN/SYN-ACK captures, ACL counters and listening socket on 8443.

Inspect NTP peers/offsets, timestamps and SNMP poll responses. This investigation primarily applies to NTP and SNMP roles during incident analysis, not the current Blocked transport port on correct host problem. Prioritize: Inspect SYN/SYN-ACK captures, ACL counters and listening socket on 8443.

Inspect route entries, subnet masks and the exact destination IP in forwarding output. This investigation primarily applies to Find matching route using longest prefix, not the current Blocked transport port on correct host problem. Prioritize: Inspect SYN/SYN-ACK captures, ACL counters and listening socket on 8443.