---
title: table.lookup_backend
summary: null
url: >-
  https://www.fastly.com/documentation/reference/vcl/functions/table/table-lookup-backend
---

```
BACKEND table.lookup_backend(ID id, STRING key, BACKEND default)
```

**Available in:** all subroutines

Looks up the key `key` in the table `id`. When the key is present, its
associated value will be returned. When the key is absent, the `default`
value is returned. The `default` value is required.

Just as for the `req.backend` variable,
both backend names and director names may be specified.

## Example

```vcl
backend b0 { .host = "203.0.113.0"; }
backend b1 { .host = "203.0.113.1"; }
backend b2 { .host = "203.0.113.2"; }

director d0 random {
  { .backend = b0; .weight = 1; }
  { .backend = b2; .weight = 1; }
}

table t BACKEND {
  "a.example.com": b0,
  "b.example.com": b1,
  "c.example.com": d0,
}

sub vcl_recv {
  set req.backend = table.lookup_backend(t, req.http.host, req.backend);
}
```