Host does not exist

What “Host does not exist” usually means

When PuTTY reports Host does not exist, the client has already attempted a network or protocol step and failed before a normal interactive shell is available. This guide explains what the message usually means on Windows clients, which local settings to verify first, and when the problem is almost certainly on the server, firewall, or DNS path rather than inside the PuTTY GUI.

The client could not resolve the hostname to an address, or the name is syntactically unusable. No TCP attempt meaningfully starts until DNS (or your hosts file) yields an IP.

Symptoms you will see

Operators usually notice this failure in one of a few repeatable ways. Capture the exact dialog text, the hostname and port from the Session panel, and whether the failure happens before or after a username prompt—those details decide which checklist below applies.

• Immediate failure naming the host as nonexistent.
• Other apps on the same PC also fail to resolve the name.

Likely causes ranked by frequency

Several independent conditions can produce the same client-facing wording. Work from the outside in: reachability first, protocol selection second, authentication third. Changing key files will not fix a TCP refusal, and opening a wider firewall will not fix a rejected public key.

• Typo in Host Name field.
• Split-horizon DNS only resolvable on VPN.
• Stale intranet name removed from DNS.
• Broken Windows DNS suffix search list.

Step-by-step client checks

Use this ordered checklist on a workstation you control. Prefer saved sessions so Host Name, Port, and Connection type stay consistent while you isolate one variable at a time.

1. Copy the hostname from inventory rather than typing from memory.
2. nslookup/dig from the same machine; compare VPN on vs off.
3. Try a known IP temporarily to separate DNS from SSH problems—then fix DNS properly.
4. Check the Windows hosts file for conflicting entries.
5. Flush DNS cache if a recent cutover occurred.
6. Save the corrected session name so the typo does not return.

When it is a server or network issue

If DNS is corporate-managed, escalate with the exact name and timestamp. Creating ad-hoc hosts file entries on every laptop does not scale and hides the real outage.

If TCP connects from another network path but fails from yours, involve the network team with traceroute/path evidence rather than repeatedly regenerating keys. If authentication fails after a banner appears, collect the server sshd logs for the same timestamp and username—client-side retries alone rarely reveal AccountLocked, Match blocks, or AllowUsers denials.

Related error guides and next steps

Continue with related Putty.info guides, then confirm any version-specific dialog labels against the official manual.

• Connection timed out
• Save a session
• Troubleshooter

Primary references: official latest download page, official PuTTY documentation, and this site's official-download redirect plus safe download guide and latest version notes.