This document lists the quotas and limits that apply to Cloud Load Balancing.
To change a quota, see requesting additional quota.
Google Cloud uses quotas to help ensure fairness and reduce spikes in resource use and availability. A quota restricts how much of a Google Cloud resource your Google Cloud project can use. Quotas apply to a range of resource types, including hardware, software, and network components. For example, quotas can restrict the number of API calls to a service, the number of load balancers used concurrently by your project, or the number of projects that you can create. Quotas protect the community of Google Cloud users by preventing the overloading of services. Quotas also help you to manage your own Google Cloud resources.
The Cloud Quotas system does the following:
- Monitors your consumption of Google Cloud products and services
- Restricts your consumption of those resources
- Provides a means to request changes to the quota value
In most cases, when you attempt to consume more of a resource than its quota allows, the system blocks access to the resource, and the task that you're trying to perform fails.
Quotas generally apply at the Google Cloud project level. Your use of a resource in one project doesn't affect your available quota in another project. Within a Google Cloud project, quotas are shared across all applications and IP addresses.
There are also limits on Cloud Load Balancing resources. These limits are unrelated to the quota system. Limits cannot be changed unless otherwise stated.
Backends
Item | Quotas and limits | Notes |
---|---|---|
Instance groups | Quota | Quotas are per-project and per-region. When making a quota increase request, select the region that contains the instance group. Zonal instance groups charge the region containing the instance group's zone. |
Zonal and regional NEGs per project | Quota | Quotas are per-project and per-region, covering all types of NEGs except for global internet NEGs, Private Service Connect NEGs, and serverless NEGs. When making a quota increase request, select the region that contains the NEG. Zonal NEGs charge the region containing the NEG's zone. |
Global NEGs per project | Quota | This quota is global, per-project, and covers global internet NEGs, Private Service Connect NEGs, and serverless NEGs. |
Maximum number of instance group backends, GCE_VM_IP_PORT
NEG backends, GCE_VM_IP NEG backends, or regional internet NEG
backends per backend service |
50 |
This limit is not configurable. Support for zonal and internet NEG backends varies by load balancing product. If you've configured failover
for backend service-based
external passthrough Network Load Balancers or if you've configured failover for
internal passthrough Network Load Balancers, you can configure up to 50 primary and 50 backup
instance groups or Internal passthrough Network Load Balancers also have a limit on the number of individual virtual machine (VM) instances or endpoints to which a backend service can distribute packets. For details, see backend services quotas. |
Endpoints per NEG
Item | Quotas and limits | Notes |
---|---|---|
Endpoints per GCE_VM_IP_PORT zonal NEG |
10,000 | This limit cannot be increased. |
Endpoints per GCE_VM_IP zonal NEG |
10,000 | This limit cannot be increased. |
Endpoints per hybrid connectivity NEG (NON_GCP_PRIVATE_IP_PORT ) |
10,000 | This limit cannot be increased. |
Endpoints per global internet NEG | 1 | This limit cannot be increased. |
Endpoints per regional internet NEG | 256 | This limit cannot be increased. |
Endpoints per serverless NEG | 1 | This limit cannot be increased. |
Endpoints per Private Service Connect NEG | 1 | This limit cannot be increased. |
Endpoints per port mapping NEG | 1,000 | This limit cannot be increased. |
VMs per instance group
The number of backend VMs that can be serviced by a single load balancer might be less than the number of VMs that an instance group can support. The maximum number of load-balanced VMs per instance group depends on the number of ports specified in each named port that the instance group exports.
By default, the upper limit of load-balanced VMs per instance group cannot exceed 2,000 for regional managed instance groups (MIGs), and cannot exceed 1,000 for zonal MIGs. In zonal unmanaged instance groups, the maximum number of VMs per group is 2,000. If you need more than 2,000 VMs, you can increase the size limit of your managed instance group or contact support.
Item | Quotas and limits | Notes |
---|---|---|
Maximum number of VMs per regional managed instance group connected to a pass-through load balancer's backend service | 2,000 | Internal passthrough Network Load Balancers also have a limit on the number of individual VM instances or endpoints to which a backend service can distribute packets. For details, see backend services quotas. |
Maximum number of VMs per zonal managed instance group or per zonal unmanaged instance group connected to a pass-through load balancer's backend service | Maximum for zonal managed instance groups: 1,000 Maximum for zonal unmanaged instance groups: 2,000 |
Internal passthrough Network Load Balancers also have a limit on the number of individual VM instances or endpoints to which a backend service can distribute packets. For details, see backend services quotas. |
Maximum number of VMs per regional managed instance group connected to a proxy load balancer's backend service | Depends on the number of ports specified in the named port for the
instance group. It is the smaller of these two: A: 2,000 B: 10,000 / (number of ports in the named port that contains the most port numbers)† |
Contact support if you need to increase this limit. |
Maximum number of VMs per zonal managed instance group connected to a proxy load balancer's backend service | Depends on the number of ports specified in the named port for the
instance group. It is the smaller of these two: A: 1,000 B: 10,000 / (number of ports in the named port that contains the most port numbers)† |
Contact support if you need to increase this limit. |
Maximum number of VMs per zonal unmanaged instance group connected to a proxy load balancer's backend service | Depends on the number of ports specified in the named port for the
instance group. It is the smaller of these two: A: 2,000 B: 10,000 / (number of ports in the named port that contains the most port numbers)† |
Contact support if you need to increase this limit. |
† To calculate the maximum number of load-balanced VMs in an instance group backend:
Determine maximum number of ports per named port.
For example, if an instance group has the following named ports:
http:80
,api-gateway:8080
, andapi-gateway:8090
, then there is one port number for thehttp
name and two port numbers for theapi-gateway
name. Therefore, in this example the maximum number of ports per named port is two.Divide 10,000 by the maximum number of ports per named port and discard the remainder. For example,
10,000 / 2 = 5,000
.Compare the number calculated in the previous step with the upper limit of load-balanced VMs per instance group: 2,000 for regional groups, 1,000 for zonal groups.
If the number calculated in the previous step is less than or equal to the upper limit, then the maximum number of load-balanced VMs per instance group is the number you calculated in the previous step. Otherwise, the maximum number of load-balanced VMs per instance group is the upper limit (2,000 for regional groups or 1,000 for zonal groups).
Target pools
Item | Quotas and limits | Notes |
---|---|---|
Target pools | Quota | This quota is per project. |
Backend buckets
Item | Quotas and limits | Notes |
---|---|---|
Backend buckets | Quota | This quota is per project. |
Backend services
To monitor backend service quotas using Cloud Monitoring, set up monitoring
for the serviceruntime.googleapis.com/quota/allocation/usage
metric on the
Consumer Quota
resource type. Set additional label filters (service
,
quota_metric
) to get to the quota type. For information about how to monitor
quota usage metrics, see
Chart and monitor quota metrics.
Item | Quotas and limits | Notes |
---|---|---|
Application Load Balancers and Proxy Network Load Balancers | ||
Classic Application Load Balancer and Classic proxy Network Load Balancer backend services | Quota | This is a per-project quota defining the maximum number of backend services for classic Application Load Balancers and classic proxy Network Load Balancers. Quota name: Available metrics:
|
Global external Application Load Balancer and Global external proxy Network Load Balancer backend services | Quota | This is a per-project quota defining the maximum number of backend services for global external Application Load Balancers and global external proxy Network Load Balancers. Quota name: Available metrics:
|
Regional external Application Load Balancer and Regional external proxy Network Load Balancer backend services |
Quota | This is a per-region and per-project quota defining the maximum number of backend services for regional external Application Load Balancers and global external proxy Network Load Balancers. Quota name: Available metrics:
|
Cross-region internal Application Load Balancer and Cross-region internal proxy Network Load Balancer backend services | Quota | This is a per-region and per-project quota defining the maximum number of backend services for cross-region internal Application Load Balancers and cross-region internal proxy Network Load Balancers. Quota name:
Available metrics:
|
Regional internal Application Load Balancer and Regional internal proxy Network Load Balancer backend services | Quota | This is a per-region and per-project quota defining the maximum number of backend services for regional internal Application Load Balancers and regional internal proxy Network Load Balancers. Quota name: Available metrics:
|
Number of backend services per Application Load Balancer | Varies based on the URL map configuration | For more details, see URL maps. |
Number of backend services per proxy Network Load Balancer | 1 | This limit cannot be changed. |
Number of named ports per Application Load Balancer or proxy Network Load Balancer backend service | 1 | This limit cannot be changed. Named ports are only relevant to instance group backends. |
Maximum distinct projects containing URL maps that can reference a particular backend service (limit relevant to cross-project service referencing) | 10 | URL maps from a maximum of 10 distinct projects can reference a particular backend service. This limit cannot be increased. This limit applies independently to each backend service. |
Passthrough Network Load Balancers | ||
External passthrough Network Load Balancer backend services | Quota | This is a per-region and per-project quota defining the maximum number of backend services for external passthrough Network Load Balancers. Quota name: Available metrics:
|
Internal passthrough Network Load Balancer backend services | Quota | This is a per-region and per-project quota defining the maximum number of backend services for internal passthrough Network Load Balancers. Quota name: Available metrics:
|
Number of backend services per passthrough Network Load Balancer | 1 | This limit cannot be changed. |
Number of named ports per passthrough Network Load Balancer backend service | 0 | This limit cannot be changed. The portName field on the
backend service is ignored for passthrough Network Load Balancers. |
Maximum number of VM instances (in all instance group backends) or
endpoints (in all GCE_VM_IP network endpoint groups) of an
internal passthrough Network Load Balancer backend service |
Without backend subsetting: 250 With backend subsetting enabled: 2000 |
These limits cannot be increased. When failover is configured, the maximum number of VM instances or endpoints applies to those in the active pool. For example, if a backend service has five instance groups, each with 60 VM instances, the load balancer only distributes packets to 250 of the 300 (5 × 60) instances when backend subsetting is turned off. |
Cloud Service Mesh | ||
Cloud Service Mesh backend services | Quota | Backend services for Cloud Service Mesh. Quota name: Available metrics:
|
Cloud Service Mesh backend services | Quota | Backend services for Cloud Service Mesh. Quota name: Available metrics:
|
Forwarding rules
To monitor forwarding rule quotas using Cloud Monitoring, set up monitoring
for the serviceruntime.googleapis.com/quota/allocation/usage
metric on the
Consumer Quota
resource type. Set additional label filters (service
,
quota_metric
) to get to the quota type. For information about how to monitor
quota usage metrics, see
Chart and monitor quota metrics.
Item | Quotas and limits | Notes |
---|---|---|
External Application Load Balancers and External proxy Network Load Balancers | ||
Classic Application Load Balancer and Classic proxy Network Load Balancer forwarding rules | Quota | This is a per-project quota defining the maximum number of forwarding rules for classic Application Load Balancers and classic proxy Network Load Balancers. If your project contains Classic VPN gateways, the forwarding rules for those gateways also count against this quota's usage. Quota name: Available metrics:
|
Global external Application Load Balancer and Global external proxy Network Load Balancer forwarding rules | Quota | This is a per-project quota defining the maximum number of forwarding rules for global external Application Load Balancers and global external proxy Network Load Balancers. Quota name: Available metrics:
|
Regional external Application Load Balancer and Regional external proxy Network Load Balancer forwarding rules per region per network This quota replaces the deprecated
per-project
|
Quota | This is a per-region and per-network quota defining the maximum number of forwarding rules for regional external Application Load Balancers and global external proxy Network Load Balancers whose backends are located in a region of a VPC network. Quota name: Available metrics:
|
Internal Application Load Balancers and Internal proxy Network Load Balancers | ||
Cross-region internal Application Load Balancer and Cross-region internal proxy Network Load Balancer forwarding rules per region per network | Quota | This is a per-region and per-network quota defining the maximum number of forwarding rules for cross-region internal Application Load Balancers and cross-region internal proxy Network Load Balancers that you can create in a region of a VPC network. Quota name:
Available metrics:
|
Regional internal Application Load Balancer and Regional internal proxy Network Load Balancer forwarding rules per region per network | Quota | This is a per-region and per-network quota defining the maximum number of forwarding rules for regional internal Application Load Balancers and regional internal proxy Network Load Balancers that you can create in a region of a VPC network. Quota name: Available metrics:
|
Cross-region internal Application Load Balancer, Regional internal Application Load Balancer, Cross-region internal proxy Network Load Balancer, and Regional internal proxy Network Load Balancer forwarding rules per network | Quota | This is a per-network quota defining the maximum number of forwarding rules for cross-region internal Application Load Balancers, regional internal Application Load Balancers, cross-region internal proxy Network Load Balancers, and regional internal proxy Network Load Balancers that you can create, in aggregate, in all regions of a VPC network. This quota is scheduled for deprecation. Quota name: Available metrics:
|
Cross-region internal Application Load Balancer, Regional internal Application Load Balancer, Cross-region internal proxy Network Load Balancer, and Regional internal proxy Network Load Balancer forwarding rules per peering group | Quota | This is a per-network quota defining the maximum number of forwarding rules for cross-region internal Application Load Balancers, regional internal Application Load Balancers, cross-region internal proxy Network Load Balancers, and regional internal proxy Network Load Balancers in all regions of a local VPC network and in all regions of all directly connected peer VPC networks. Quota name: Available metrics:
|
Passthrough Network Load Balancers | ||
External passthrough Network Load Balancer forwarding rules (per project) | Quota | This is a per-project quota defining the maximum number of forwarding rules for external passthrough Network Load Balancers (both backend service and target pool architectures). Quota name: Available metrics:
|
Internal passthrough Network Load Balancer forwarding rules per network | Quota | This is a per-network quota defining the maximum number of forwarding rules for internal passthrough Network Load Balancers that you can create, in aggregate, in all regions of a VPC network. Quota name: Available metrics:
|
Internal passthrough Network Load Balancer forwarding rules per peering group | Quota | This is a per-network quota defining the maximum number of forwarding rules for internal passthrough Network Load Balancers in all regions of a local VPC network and in all regions of all directly connected peer VPC networks. Quota name: Available metrics:
|
Number of discrete ports per forwarding rule for internal passthrough Network Load Balancers and backend service-based external passthrough Network Load Balancers | 5 |
This is a limit, and it cannot be changed. Alternative port specification options are possible:
|
Number of forwarding rules that can reference the same backend service for a pass-through load balancer | No separate limit | Subject to other quotas and limits, multiple forwarding rules can reference the same backend service for a pass-through load balancer. |
Number of pass-through load balancer backend services that can be referenced by a single forwarding rule | 1 | Forwarding rules for pass-through load balancers must reference exactly one backend service. |
Maximum number of internal forwarding rules that can share a single internal IP address | 10 | This limit is only applicable to internal passthrough Network Load Balancers. This limit cannot be increased. |
Protocol forwarding (target instances) | ||
External protocol forwarding rules (per project) | Quota | This is a per-project quota defining the maximum number of external protocol forwarding rules. Quota name: Available metrics:
|
Internal protocol forwarding rules per network | Quota | This is a per-network quota defining the maximum number of forwarding rules for internal protocol forwarding that you can create, in aggregate, in all regions of a VPC network. Quota name: Available metrics:
|
Internal protocol forwarding rules per peering group | Quota | This is a per-network quota defining the maximum number of internal protocol forwarding rules in all regions of a local VPC network and in all regions of all directly connected peer VPC networks. Quota name: Available metrics:
|
Cloud Service Mesh | ||
Cloud Service Mesh forwarding rules | Quota | Forwarding rules for Cloud Service Mesh. Quota name: Available metrics:
|
Target proxies
Item | Quotas and limits | Notes |
---|---|---|
Target HTTP proxies | Quota | This quota is per project. |
Target HTTPS proxies | Quota | This quota is per project. |
Target SSL proxies | Quota | This quota is per project. |
Target TCP proxies | Quota | This quota is per project. |
SSL policies per target HTTPS or target SSL proxy | 1 | This limit cannot be increased. |
SSL certificates per target HTTPS or target SSL proxy | 15 | This limit cannot be increased; however, some load balancers support Certificate Manager, which provides a way for a target HTTPS proxy or target SSL proxy to use thousands of SSL certificates. For more information, see Multiple SSL certificates in the SSL certificates overview. |
Health checks
Item | Quotas and limits | Notes |
---|---|---|
Health checks | Quota | This is a per-project quota covering all health check types (global, regional, and legacy). |
URL maps
The limits documented here cannot be increased.
Item | External Application Load Balancer | Internal Application Load Balancer |
---|---|---|
URL maps | Quota
This quota is per project. |
Quota
This quota is per project. |
Host rules, path matchers per URL map | Limit: 1000 | Limit: 2000 |
Path rules or route rules per path matcher | Limit: 1000 | Limit: 1000 |
Hosts per host rule | Limit: 1000 | Limit: 1000 |
Predicates per path matcher † | Limit: 1000 | Limit: 1000 |
pathTemplateMatch predicates per path matcher |
Global external Application Load Balancers and regional external Application Load Balancers: Limit: 100 Not supported for classic Application Load Balancers |
Limit: 100 |
Number of distinct backend services or backend buckets that can be referenced by a URL map | Limit: 2500 | Limit: 2500 |
Other limits relevant to cross-project service referencing:
|
||
Size of URL maps | Limit: 64 KB | Limit: 128 KB |
Number of URL map tests | Classic Application Load Balancer: Limit: 10000 |
N/A
Internal Application Load Balancers don't support URL map tests. |
Global external Application Load Balancer and Regional external Application Load Balancer: Limit: 100 |
† This is a limit on the count of match conditions across all rules in the path matcher. For path matchers with path rules, this is the total number of paths across all path rules. For path matchers with route rules, the prefix count is calculated by adding the following:
- 1 for the path match condition (one of prefixMatch or fullPathMatch)
- the sum of header matches in all route rules of the path matcher
- the sum of query parameter matches in all route rules of the path matcher
For example, for a path matcher with the following route rules:
- Route rule A having one prefixMatch and three header matches
- Route rule B having one fullPathMatch and two query parameter matches
The total count of predicates for this path matcher would be 7. This is calculated as follows: 1 (for the prefixMatch) + 3 (for the number of header matches) + 1 (for the fullPathMatch) + 2 (for the number of query parameter matches).
Header size for Application Load Balancers
Item | Quotas and limits | Notes |
---|---|---|
Maximum client request header size for external Application Load Balancers | 64 KB (kilobytes) | This limit cannot be increased. The combined size of the request URL and request header must be less than or equal to 64 KB. |
Maximum backend response header size for external Application Load Balancers | About 128 KB (kilobytes) | This limit cannot be increased. |
Maximum backend request header size for internal Application Load Balancers | 60 KB (kilobytes) | This limit cannot be increased. |
Lowercase conversion of HTTP request and response headers | Always, except for Classic Application Load Balancer when using HTTP/1.1 | As examples, Host
becomes host , and Keep-ALIVE becomes
keep-alive . |
Maximum number of configured custom request headers for each backend service | 16 | This limit cannot be increased. |
Maximum number of configured custom response headers for each backend service | 16 | This limit cannot be increased. |
Total size of all custom request headers per backend service (name and value combined, before variable expansion) | 8 KB | This limit cannot be increased. |
Total size of all custom response headers per backend service (name and value combined, before variable expansion) | 8 KB | This limit cannot be increased. |
Queries per second for Application Load Balancers
Item | Quotas and limits | Notes |
---|---|---|
Queries per second (QPS) per backend instance group or NEG for global external Application Load Balancers | Configurable when using RATE for the balancing mode. |
Limited by your backends. |
Queries per second (QPS) per region per network for regional external Application Load Balancers | For regional external Application Load Balancers, the maximum QPS load depends on the size of the requests and the complexity of the configuration. If load exceeds capacity, latency increases and requests might be dropped. | Limited by your backends.* Contact support if you need to increase this limit. |
Queries per second (QPS) per region per network for internal Application Load Balancers | For internal Application Load Balancers, the maximum QPS load depends on the size of the requests and the complexity of the configuration. If load exceeds capacity, latency increases and requests might be dropped. | Limited by your backends.* Contact support if you need to increase this limit. |
* For projects that are using serverless NEGs, the limit is 5000 queries per second (QPS) per project for traffic sent to any serverless NEGs configured with regional external Application Load Balancers or regional internal Application Load Balancers. This limit is aggregated across all regional external Application Load Balancers and regional internal Application Load Balancers in a project and region. This is not a per load balancer limit.
Service load balancing policy
Item | Quotas and limits | Notes |
---|---|---|
ServiceLbPolicies | Quota | This quota is per project and applies to classic Application Load Balancers and global external Application Load Balancers. |
SSL certificates
Item | Quotas and limits | Notes |
---|---|---|
SSL certificates | Quota | This quota is per project. |
Supported key lengths for private keys | 2048 bit RSA (RSA-2048) 256 bit ECDSA (ECDSA P-256) |
These limits cannot be increased. |
Multiple domains per Google-managed SSL certificate | 100 | This limit cannot be increased. |
Domain name length for Google-managed certificates | 64 bytes | This limit cannot be increased. This length limit only applies to Google-managed SSL certificates. In those certificates, the 64-byte limit only applies to the first domain in the certificate. The length limit for the other domains in the certificate is 253, which applies to any domain name on the internet, and isn't specific to Google-managed certificates. |
SSL policies
Item | Quotas and limits | Notes |
---|---|---|
Global SSL policies | Quota | This quota is per project. This quota is used by:
|
Regional SSL policies | Quota | This quota is per region, per project. This quota is used by:
|
Server TLS policy
Item | Quotas and limits | Notes |
---|---|---|
ServerTLSPolicy | Quota | This quota is per project and applies to classic Application Load Balancers and global external Application Load Balancers. |
Trust config
The limits documented here cannot be increased and apply to classic Application Load Balancers and global external Application Load Balancers.
Item | Quotas and limits | Notes |
---|---|---|
Number of trust stores | Limit: 1 | This limit is per TrustConfig resource. |
Number of trust anchors | Limit: 100 | This limit is per trust store. |
Number of intermediate certificates | Limit: 100 | This limit is per trust store. |
Number of name constraints allowed during validation of root and intermediate certificates | Limit: 10 | |
Intermediate certificates that share the same Subject and Subject Public Key information | Limit: 10 | This limit is per trust store. |
Certificate chain depth | Limit: 10 | The maximum depth for a certificate chain, including the root and client certificates. |
Number of times intermediate certificates can be evaluated when attempting to build the chain of trust | Limit: 100 | |
Keys of certificates uploaded and passed from the client | Limit: RSA keys can be from 2048 to 4096 bits ECDSA certificates must use either P-256 or P-384 curves |
Public delegated prefix limits
The limits documented here apply to external passthrough Network Load Balancers.
Item | Quotas and limits | Notes |
---|---|---|
Public delegated prefix with variable prefix length | Quota | This quota is per project. This is a quota for the number of
public delegated prefixes (PDPs) whose Customers get a default quota of 40. |
Manage quotas
Cloud Load Balancing enforces quotas on resource usage for various reasons. For example, quotas protect the community of Google Cloud users by preventing unforeseen spikes in usage. Quotas also help users who are exploring Google Cloud with the free tier to stay within their trial.
All projects start with the same quotas, which you can change by requesting additional quota. Some quotas might increase automatically based on your use of a product.
Permissions
To view quotas or request quota increases, Identity and Access Management (IAM) principals need one of the following roles.
Task | Required role |
---|---|
Check quotas for a project | One of the following:
|
Modify quotas, request additional quota | One of the following:
|
Check your quota
Console
- In the Google Cloud console, go to the Quotas page.
- To search for the quota that you want to update, use the Filter table. If you don't know the name of the quota, use the links on this page instead.
gcloud
Using the Google Cloud CLI, run the following command to
check your quotas. Replace PROJECT_ID
with your own project ID.
gcloud compute project-info describe --project PROJECT_ID
To check your used quota in a region, run the following command:
gcloud compute regions describe example-region
Errors when exceeding your quota
If you exceed a quota with a gcloud
command,
gcloud
outputs a quota exceeded
error
message and returns with the exit code 1
.
If you exceed a quota with an API request, Google Cloud returns the
following HTTP status code: 413 Request Entity Too Large
.
Request additional quota
To increase or decrease most quotas, use the Google Cloud console. For more information, see Request a higher quota.
Console
- In the Google Cloud console, go to the Quotas page.
- On the Quotas page, select the quotas that you want to change.
- At the top of the page, click Edit quotas.
- For Name, enter your name.
- Optional: For Phone, enter a phone number.
- Submit your request. Quota requests take 24 to 48 hours to process.
Resource availability
Each quota represents a maximum number for a particular type of resource that you can create, if that resource is available. It's important to note that quotas don't guarantee resource availability. Even if you have available quota, you can't create a new resource if it is not available.
For example, you might have sufficient quota to create a new regional, external IP address
in the us-central1
region. However, that is not possible if there are no
available external IP addresses in that region. Zonal resource
availability can also affect your ability to create a new resource.
Situations where resources are unavailable in an entire region are rare. However, resources within a zone can be depleted from time to time, typically without impact to the service level agreement (SLA) for the type of resource. For more information, review the relevant SLA for the resource.