fix(yield): Check multiple DNS servers to handle propagation delays

backend/app/services/yield_dns.py

@@ -29,13 +29,20 @@ class YieldDNSCheckResult:
     error: Optional[str]
 
 
-def _resolver() -> dns.resolver.Resolver:
+def _resolver(nameserver: str | None = None) -> dns.resolver.Resolver:
+    """Create a DNS resolver, optionally using a specific nameserver."""
     r = dns.resolver.Resolver()
+    if nameserver:
+        r.nameservers = [nameserver]
     r.timeout = 3
     r.lifetime = 5
     return r
 
 
+# Multiple public DNS servers to check (for propagation consistency)
+PUBLIC_DNS_SERVERS = ['8.8.8.8', '8.8.4.4', '9.9.9.9', '1.1.1.1']
+
+
 def _normalize_host(host: str) -> str:
     return host.rstrip(".").lower().strip()
 
@@ -58,6 +65,23 @@ def _resolve_a(host: str) -> list[str]:
     return sorted({str(rr) for rr in answers})
 
 
+def _resolve_a_from_multiple_dns(host: str) -> set[str]:
+    """
+    Resolve A records from multiple public DNS servers.
+    Returns the union of all IPs found (handles propagation delays).
+    """
+    all_ips: set[str] = set()
+    for ns in PUBLIC_DNS_SERVERS:
+        try:
+            r = _resolver(ns)
+            answers = r.resolve(host, "A")
+            for rr in answers:
+                all_ips.add(str(rr))
+        except Exception:
+            continue
+    return all_ips
+
+
 def verify_yield_dns(domain: str, expected_nameservers: list[str], cname_target: str) -> YieldDNSCheckResult:
     """
     Verify that a domain is connected for Yield.
@@ -84,9 +108,11 @@ def verify_yield_dns(domain: str, expected_nameservers: list[str], cname_target:
         )
 
     # Option A: Direct A-record to our server IP (SIMPLEST!)
+    # Check multiple DNS servers to handle propagation delays
     try:
-        actual_a = _resolve_a(domain)
-        if YIELD_SERVER_IP in actual_a:
+        all_ips = _resolve_a_from_multiple_dns(domain)
+        actual_a = sorted(all_ips)
+        if YIELD_SERVER_IP in all_ips:
             return YieldDNSCheckResult(
                 verified=True,
                 method="a_record",
@@ -95,8 +121,6 @@ def verify_yield_dns(domain: str, expected_nameservers: list[str], cname_target:
                 cname_ok=False,
                 error=None,
             )
-    except (dns.resolver.NXDOMAIN, dns.resolver.NoAnswer):
-        pass
     except Exception as e:
         return YieldDNSCheckResult(
             verified=False,