Network & Email · page 16

Formats http_proxy, HTTPS_PROXY, and NO_PROXY values correctly.

Plans overlay addressing and gateway nodes for mesh deployments.

Plans rekey lifetimes and margins to avoid simultaneous rekeys.

Plans FQDN versus IP identities and PSK mapping per peer.

Scores PSK length and entropy offline and suggests stronger passphrases.

Compares hub-spoke, partial mesh, and full mesh VPN designs.

Reviews remote access VPN posture, groups, and split rules.

Plans identity-based tunnel policies replacing flat network access.

Parses pasted ping stats for loss, min, avg, max, and mdev outliers.

Grades RTT and loss against LAN, metro, and internet expectations.

Explains each hop line including timeouts and MPLS label segments.

Flags asymmetry, premature timeouts, and likely filter points.

Highlights lossy hops and stdev outliers from pasted MTR output.

Plans DF-set ping probes per hop to locate the PMTU.

Decision tree for large-packet hangs caused by PMTU black holes.

Explains SYN, SYN-ACK, and ACK timing from pasted capture lines.

Explains window scaling and in-flight bytes from pasted output.

Triages dup-ACK, RTO, and SACK patterns into likely causes.

Explains dig answer sections, header flags, and TTL values.

Tables NOERROR, NXDOMAIN, SERVFAIL, and REFUSED meanings.

Flags duplicates and ghost entries in pasted arp output.

Triages duplicate-IP and ARP flapping symptoms step by step.

References RS, RA, NS, and NA messages with DAD notes.

Tables ICMP types and codes with firewall guidance.