Diagnostics
The core troubleshooting toolkit. All five tools in this chapter take a hostname or an IPv4/IPv6 address and produce streaming results.
Ping
A standard ICMP echo — "is this host alive, and how fast?". DR-NetTools uses its own cross-platform Pinger, not the system ping binary, so behaviour is identical on every platform.
- Input — hostname, IPv4, IPv6. Autofill remembers recent targets.
- Live graph — RTT in milliseconds, one point per ICMP sequence number. Holds up to 1000 samples, then scrolls.
- Result list — icmp_seq, bytes, RTT, timestamp. Failed attempts show as a red row and a zero-point on the graph.
- Average time — updated after every reply, calculated over successful replies only.
- Sound feedback — a beep bar above the graph: Off, On success, or On failure. Useful when you're under a desk and want to know when a cable goes in without looking.
Packet size (default 32 bytes, range 24–1024) and timeout (default 1 s, range 1–2147 s) are global — Settings → Defaults. Changing them affects the next ping run.
Reading the results
- Low, stable RTT — link healthy.
- Occasional spikes — usually normal queueing; watch for patterns (every ~N replies) that hint at buffer-bloat or radio retransmits.
- Periodic losses — flaky link, duplex mismatch or congestion. Cross-check with Traceroute and MTR.
- All losses — host down, firewall dropping ICMP, wrong route. Try a TCP probe with Port scanner on a known-open port.
Traceroute
Shows the path packets take to the destination, one hop at a time. Each hop displays the IP, resolved hostname (where possible) and response time; the GeoIP database adds country/city/ISP context for public addresses.
- Input — hostname or IP. IPv4 and IPv6 both supported.
- Results stream — new hops appear as the probe moves forward. An asterisk (no reply) means the router dropped the TTL-expired response — expected for some firewalls, not a failure.
- Last hop — when it matches the target you've reached it. Otherwise the trace stops at the TTL limit.
GeoIP annotations use the DR-ONLINE resolver (rate-limited, cached). Private addresses are not looked up.
MTR (continuous traceroute)
MTR — My Traceroute — keeps probing every hop in a loop, so you see per-hop loss percentage and jitter over time, not just a single snapshot. Best tool for "packets are being dropped somewhere, but where?".
- Input — as Traceroute.
- Columns — hop #, host, Loss%, Snt (packets sent), Last, Avg, Best, Wrst, StDev.
- Interpretation — loss at an intermediate hop that does not continue to the next one usually means that router is rate-limiting ICMP and is not actually dropping forwarded traffic. Loss that continues to the destination is real.
- Jitter — high StDev on the final hop points at a noisy last mile (Wi-Fi, ADSL).
Tap Stop when you've seen enough — the table freezes and the results can be shared or copied.
DNS lookup
A full-featured client resolver. Supports every record type the network library can decode — A, AAAA, NS, CNAME, SOA, PTR, HINFO, MX, TXT, SRV, NAPTR, DS, RRSIG, NSEC, NSEC3, DNSKEY — and offers a single-query or "query them all" mode.
- Domain — the name you want to resolve.
- Record type — pick one from the dropdown, or toggle All to sweep through every supported type and merge answers.
- Resolver — optional. Empty uses Cloudflare
1.1.1.1; fill in anything (8.8.8.8, your AD DC, an internal resolver) to query it directly — handy for split-horizon debugging.
DNSSEC records (DS, RRSIG, NSEC, DNSKEY) are fetched and displayed raw — the app does not validate signatures. Use them to confirm the zone is signed, not to establish trust.
Common gotchas
- Empty answer but no error — the type isn't defined for the name (e.g. no AAAA, IPv6-less zone).
- Different resolvers, different answers — check TTL, geo-aware routing (Akamai, Cloudflare), or internal split-DNS.
- NXDOMAIN — name simply doesn't exist. Typo or a delegation issue upstream.
Reverse DNS (rDNS)
Maps an IP back to a PTR record (X.X.X.X.in-addr.arpa for IPv4, *.ip6.arpa for IPv6). Input is an IP; optional resolver field behaves the same as in DNS lookup.
- Returns the PTR answer(s) — typically the forward-confirmed hostname of the address owner.
- No result is common — many ISPs don't publish PTRs for dynamic ranges.
- On an IP you own, mismatched forward/reverse is a flag for mail delivery (SPF/DMARC care, receiving servers care).
RTT, TTL, loss, jitter — a glossary
| Term | What it means |
|---|---|
| RTT (round-trip time) | Time for a packet to reach the target and a reply to come back. |
| TTL (time to live) | Countdown in the IP header, decremented by each router. At 0 the packet is dropped — that's how Traceroute finds hops. |
| Loss | Percentage of probes without a reply. |
| Jitter | Variation between consecutive RTTs. High jitter hurts VoIP, gaming, real-time video. |
| ICMP seq | Ping packet sequence number — useful for matching a loss to a moment in time. |