DNS

2 SERVFAIL

Server failure. The name server encountered an internal error while processing the query.

On this page

When You See This Code

The recursive resolver could not get an authoritative answer — commonly caused by DNSSEC validation failures, unreachable upstream nameservers, or misconfigured zones.

How to Fix

Try a different resolver (e.g., 8.8.8.8 or 1.1.1.1) to isolate the issue. If you control the zone, check DNSSEC signatures, SOA serial consistency, and nameserver reachability.

Specification

View RFC / Specification →

Cross-Protocol Equivalents

HTTP 500 Internal Server Error

Comparisons

DNS SERVFAIL (RCODE 2) vs REFUSED (RCODE 5)

Compare With

0 NOERROR 1 FORMERR 3 NXDOMAIN 4 NOTIMP 5 REFUSED 6 YXDOMAIN 7 YXRRSET 8 NXRRSET 9 NOTAUTH 10 NOTZONE 11 DSOTYPENI 16 BADVERS/BADSIG

Guides

HTTP Request Lifecycle: From URL to Response HTTP Fundamentals

Step-by-Step DNS Troubleshooting with dig and nslookup Debugging & Troubleshooting

Improving Email Deliverability: SPF, DKIM, and DMARC Setup Email Delivery

DNS Response Codes (RCODEs) Explained DNS & Networking

DNS TTL: How to Set TTL Values and Avoid Propagation Delays DNS & Networking

DNS Propagation: Why Changes Take Time DNS & Networking

DNSSEC Implementation Guide DNS & Networking

DNS-Based Failover and High Availability DNS & Networking

DNS Record Types Explained: A, AAAA, CNAME, MX, TXT, and Beyond DNS & Networking

DNS over HTTPS (DoH) and DNS over TLS (DoT): Encrypted DNS Explained DNS & Networking

Essential Network Debugging Tools: ping, traceroute, mtr, and tcpdump DNS & Networking

Resource Hints: Preload, Prefetch, Preconnect, and DNS-Prefetch Performance & Optimization

RFC 9114: HTTP/3 Protocol Deep Dive Protocol Deep Dives

RFC 3261: SIP Protocol Deep Dive Protocol Deep Dives

QUIC Protocol: The Transport Layer Behind HTTP/3 Protocol Deep Dives

Migrating from TLS 1.2 to TLS 1.3: Configuration and Compatibility Migration & Upgrades

Secret Management for API Keys, Tokens, and Certificates Production Infrastructure

Debugging Scenarios

NXDOMAIN — Domain Does Not Exist Beginner

REFUSED — Recursive Query to Authoritative-Only Server Intermediate

NXDOMAIN — Subdomain Typo or Missing DNS Record Beginner

SERVFAIL — Lame Delegation Advanced

FORMERR — Malformed DNS Query Intermediate

High TTL Causing Delayed DNS Failover Intermediate

NOTAUTH — Unauthorized DNS Dynamic Update Advanced

Specifications

RFC 1035 Domain Names - Implementation and Specification

Decision Guides

Why Is DNS Resolution Failing?

Glossary

TCP/IP Port Number Latency Timeout Firewall DNS over HTTPS (DoH) IPv6 Subnet (Subnetwork) MTU (Maximum Transmission Unit) UDP (User Datagram Protocol) DNS Lookup CDN (Content Delivery Network) Request-Response Model RFC (Request for Comments) IANA (Internet Assigned Numbers Authority) Wire Format Extension Mechanism Connectionless Text vs Binary Protocol DNS Resolution DNS Record Types TTL (Time to Live) DNSSEC (DNS Security Extensions) DNS over TLS (DoT) Anycast Recursive Resolver Authoritative Name Server Glue Record EDNS(0) DNS Zone DNS Propagation CNAME Record MX Record SRV Record PTR Record DNS Cache Poisoning DNS Root Server Split-Horizon DNS Wildcard DNS Record SPF, DKIM, and DMARC Email Deliverability MTA (Mail Transfer Agent) ARC (Authenticated Received Chain) BIMI (Brand Indicators for Message Identification) Service Discovery GSLB (Global Server Load Balancing) Failover Active-Passive HA

Frequently Asked Questions

What is DNS 2 SERVFAIL?

Server failure. The name server encountered an internal error while processing the query.

When do you see DNS 2 SERVFAIL?

The recursive resolver could not get an authoritative answer — commonly caused by DNSSEC validation failures, unreachable upstream nameservers, or misconfigured zones.

How to fix DNS 2 SERVFAIL?

Try a different resolver (e.g., 8.8.8.8 or 1.1.1.1) to isolate the issue. If you control the zone, check DNSSEC signatures, SOA serial consistency, and nameserver reachability.