# DNS resolution 재현 — variant=strict mode=mode2

**Date:** 2026-07-01_195854  · **ns:** dns-lab · **cluster:** homelab · backend-a=10.250.147.30 backend-b=10.250.27.55

> 초안(construction 로그). 기대 vs 실제 판정표가 아니라 '무엇을 어떻게 했고 그때 무엇이 보였나' 기록.

## 1. 변형 적용
적용: SE=strict, VS=80to443(no-retry), DR=tls(no-outlier)

## 2. BEFORE (gslb -> A,B 둘 다; STRICT는 endpoint 2개)
### before
```
dig     : 10.250.27.55 
-- endpoints --
ENDPOINT             STATUS      OUTLIER CHECK     CLUSTER
10.250.27.55:443     HEALTHY     OK                outbound|443||gslb.lab.internal
-- stats --
[cluster|443 cx]
.membership_change: 5
.upstream_cx_active: 0
.upstream_cx_connect_fail: 0
.upstream_cx_destroy: 8
.upstream_cx_destroy_local: 4
.upstream_cx_destroy_local_with_active_rq: 0
.upstream_cx_destroy_remote: 4
.upstream_cx_destroy_remote_with_active_rq: 0
.upstream_cx_destroy_with_active_rq: 0
.upstream_cx_total: 8
[endpoint|443 cx]
10.250.27.55:443::cx_active::0
10.250.27.55:443::cx_total::0
10.250.27.55:443::rq_total::0
10.250.27.55:443::health_flags::healthy
```

## 3. backend-a kill (DNS엔 A 잔존 = 죽은 IP)
### 3a. no-outlier/no-retry 구간 유실
10:59:08 who=backend-b code=200
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10:59:23 who=backend-b code=200

## 4. 복구: outlier(DR44) + retry(VS45) 적용
### 4a. 복구 후 구간
10:59:32 who=backend-b code=200
10:59:32 who=backend-b code=200
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## 5. AFTER
### after
```
dig     : 10.250.147.30 10.250.27.55 
-- endpoints --
ENDPOINT              STATUS      OUTLIER CHECK     CLUSTER
10.250.147.30:443     HEALTHY     OK                outbound|443||gslb.lab.internal
10.250.27.55:443      HEALTHY     OK                outbound|443||gslb.lab.internal
-- stats --
[cluster|443 cx]
.membership_change: 6
.upstream_cx_active: 0
.upstream_cx_connect_fail: 0
.upstream_cx_destroy: 8
.upstream_cx_destroy_local: 4
.upstream_cx_destroy_local_with_active_rq: 0
.upstream_cx_destroy_remote: 4
.upstream_cx_destroy_remote_with_active_rq: 0
.upstream_cx_destroy_with_active_rq: 0
.upstream_cx_total: 8
[endpoint|443 cx]
10.250.147.30:443::cx_active::0
10.250.147.30:443::cx_total::0
10.250.147.30:443::rq_total::0
10.250.147.30:443::health_flags::healthy
10.250.27.55:443::cx_active::0
10.250.27.55:443::cx_total::0
10.250.27.55:443::rq_total::0
10.250.27.55:443::health_flags::healthy
```

## 6. 읽는 법: 3a에서 code!=200(연결실패=유실) 비율 vs 4a에서 0 수렴.

## 원상복구 힌트
```
kubectl -n dns-lab scale deploy/backend-a --replicas=1
kubectl -n dns-lab apply -f /home/jinsoo/Documents/kakaopay/istio/scenarios/50-dns-resolution/42-virtualservice-80to443.yaml -f /home/jinsoo/Documents/kakaopay/istio/scenarios/50-dns-resolution/43-destinationrule-tls.yaml
```